|
|
|
||
|
| |
||
|
|||
|
|
 |
Abstracts Effect of feeding systems on composition and organoleptic quality of goat milk cheese This study investigated effects of different feeding systems on chemical and biochemical composition and organoleptic scores of a goat milk soft cheese. Three groups of lactating Alpine goats (BW = 54 ± 10 kg) grazed with different levels of concentrate supplementation on pasture (A: no concentrate; B: 0.33 kg concentrate; C: 0.66 kg concentrate) and the fourth group (D) was confined and fed 0.66 kg concentrate and alfalfa hay ad libitum. Ten kg of milk from each group was collected and made into a soft cheese twice monthly from April through September 2001. Cheese samples were analyzed for fatty acid, fat, and protein contents, and were evaluated for sensory quality when fresh and 1 and 2 mo later. Results indicated that feeding system did not affect fat or protein content in cheese on dry basis at any age (P > 0.05). However, there were significant differences in total fatty acid concentrations and sensory scores (P < 0.05), especially when fresh and at 1 mo of age. Significant differences were also found in fat, protein, and total fatty acid concentrations and in sensory scores of soft cheese at different stages of lactation. The cheeses showed higher fat content and higher total fatty acid concentration in early and late lactation compared with mid-lactation (P < 0.01). The total organoleptic score (body, texture, and flavor) increased linearly (P < 0.01) as lactation progressed. Cheese from A had more abundant short-chain (C6 to C10) fatty acids than cheese from D (P > 0.05). Negative correlations were found between total fatty acid concentration and sensory scores (r = -0.20 to -0.28) at all ages. In conclusion, milk from grazing goats supplemented with a high level of concentrate resulted in cheese with a higher total fatty acid content, lower short-chain fatty acid concentration, and lower sensory score of cheese compared with milk from goats without or with a low level of supplemental concentrate. Effect of ruminally degraded nitrogen source and level in a high concentrate diet on site of
digestion in Boer x Spanish wethers Eight yearling Boer x Spanish goat wethers (35.3 ± 6.6 kg average initial BW) with ruminal and duodenal cannulas were used in an experiment with two simultaneous 4 x 4 Latin squares to study effects of supplemental ruminally degraded N (DIP) source and level on sites of digestion. Diets were (DM basis) 9.2% CP, without inclusion of urea (U0) or soybean meal (S0); 11.3% CP achieved with 0.73% urea (U1) or 4.48% soybean meal (SBM; S1); 13.3% CP via use of 1.46% urea (U2) or 8.90% SBM (S2); or 15.2% CP derived through use of 2.16% urea (U3) or 13.2% SBM (S3). The ratio of DIP:TDN was 0.073, 0.104, 0.136, 0.167, 0.073, 0.093, 0.113, and 0.132 for U0, U1, U2, U3, S0, S1, S2, and S3, respectively. Diets contained 30% cottonseed hulls and were corn-based and fed at 2% BW (DM basis). Microbial OM and N flows to the duodenum linearly decreased as (P < 0.05) CP level increased (N: 8.8, 7.6, 7.8, 6.7, 7.4, 6.0, 6.7, and 6.7 g/d for U0, U1, U2, U3, S0, S1, S2, and S3, respectively). Apparent ruminal OM digestibility increased linearly as CP level increased, and there was an interaction between the quadratic effect of CP level and source in total tract OM digestibility (P < 0.05). With urea diets, total tract OM digestibility plateued at U1, while the peak with SBM was at S2 (71.3, 78.0, 77.7, 77.8, 71.5, 73.1, 74.7, and 75.0% for U0, U1, U2, U3, S0, S1, S2, and S3, respectively; SE = 0.14). There were interactions between linear and quadratic effects of CP level and source in true ruminal and postruminal N digestibilities (P < 0.08). With urea diets, true ruminal N digestibility linearly increased and postruminal N digestibility linearly decreased as CP level rose, whereas there were marked effects of SBM inclusion but no differences among S1, S2, and S3. Ruminal and total tract NDF digestibilities (total tract: 51.3, 57.6, 57.7, 57.4, 49.7, 52.3, 53.2, and 53.2% for U0, U1, U2, U3, S0, S1, S2, and S3, respectively) increased linearly (P < 0.05) with increasing CP level, although differences tended to be greater for urea or SBM inclusion than among U1, U2, and U3 or S1, S2, and S3 (quadratic, P <0.13). In conclusion, N recycling in yearling goats appears adequate to support high microbial growth with a high concentrate diet, although OM and NDF digestion may be enhanced by additional DIP for a DIP:TDN ratio of 0.10 to 0.11. Supported by USDA project No. 98-38814-6240. Effect of clinical Staphylococcus aureus mastitis on early lactation dairy goats A study was conducted to characterize the effect of induced Staphylococcus aureus mastitis on physical parameters and milk constituents of first lactation Alpine dairy goats in early lactation (22 d in milk). The right udder half of seven goats was challenged with approximately 120 colony-forming units of S. aureus. Seven additional goats were not challenged and served as control animals. All goats were free of mastitis at the start of the experiment. Milk samples from each half of all goats were collected immediately prior to challenge (0 h) and at 24, 48, and 72 h postchallenge for somatic cell count (SCC) and composition analysis (fat and protein). Rectal temperature and milk yield were also monitored at the time interval above. Acute clinical mastitis occurred within 24 h postchallenge, and clinical symptoms and the infection persisted through 72 h. The logarithm of milk SCC from challenged halves was higher (6.75, P < 0.05, right half) than adjacent halves (6.01, left half) and the SCC of adjacent halves was higher than that of control animals (5.82, P < 0.05) at 24 h postchallenge. At 48 h and 72 h, SCC of milk from challenged halves remained elevated (6.86 and 6.96) above those of adjacent halves (5.89 and 5.88, P < 0.05) and control animals (5.79 and 5.88, P < 0.05). The percentage of milk fat from challenged halves was depressed only at 24 h postchallenge when compared with milk from adjacent halves and control group goats (3.55 versus 3.92 and 4.23, P < 0.05). However, the percentage of proteins in milk was higher (P < 0.05) in both infected and adjacent halves when compared with milk from control goats at 24 h (3.60 and 3.16 versus 2.76), 48 h (3.86 and 3.54 versus 2.72), and 72 h (3.57 and 3.66 versus 2.66). The rectal temperature of challenged goats peaked at 24 h (40.6C, P < 0.05) and returned to normal values by 48 h and 72 h (39.7C and 39.2C). Milk yields of infected goats were depressed at 24 and 48 h postchallenge when compared with control goats (P < 0.05) and recovered to prechallenge levels by 72 h. Results indicate that clinical mastitis in one udder half can influence physiological parameters in the adjacent half. Therefore, consideration must be given to both udder halves when evaluating the mammary gland health status of dairy goats. Variation in browse nutrient content in western Oklahoma throughout the growing season Leaves of browse species were sampled from May to September in west central (WC) and western OK (W) to determine changes in chemical composition throughout a growing season. Shinnery oak (SH, Quercus havardi) and sumac (SU, Rhus copallina) were sampled at each site. Blackjack oak (BK, Q. marilandica) and post oak (PK, Q. stellata) were sampled in WC and locust (LC, Gleditsia triacanthos), sand plum (SP, Prunus angustifolia), and skunkbush (SK, R. aromatica) in W. Sites were divided into three areas for sampling with three replications taken of each species in each area, frozen, and freeze dried. Samples were analyzed for DM, ash, N, NDF, ADF, ADL, and true IVDMD (NDF as end-point measure). The DM percentage tended to increase throughout the growing season (P < 0.01). There was a species by date interaction (S x D) in ash concentration (P < 0.01), with level increasing through mid-summer and then stabilizing or declining slightly. There was no difference in N level among WC species (P > 0.05), and N level was lowest in August (S x D; P < 0.01). In W, LC had higher N (P < 0.01) compared with other species. In WC, oak species had higher NDF, ADF, and ADL throughout the growing season compared with SU (P < 0.05), while in W NDF concentrations ranked SH > LC > SU, SK, and SP (P < 0.05). NDF in WC was highest in July and decreased thereafter, whereas in W, NDF concentration tended to increase throughout the growing season (S x D; P < 0.01). IVDMD of oak species in WC was lower (P < 0.05) than in SU throughout the collection period. Exceptionally high IVDMD, over 90%, was recorded for SU in both WC and W. Trends in nutrient content found over a 5- month sampling period indicate that, in general, tree leaves decrease in N concentration and increase in fiber and lignin contents. Prediction of energy requirements for maintenance and gain of growing goats Literature data were compiled and a database was constructed to estimate ME requirements for maintenance (MEm) and BW gain (MEg) for three different biotypes of growing goats (i.e., > 50% Boer or meat, dairy, and indigenous) by regressing ME intake (MEI, kJ/kg BW0.75) against ADG (g/kg BW0.75). Because of differences among biotypes in intercepts and slopes (P < 0.05), data subsets for the different biotypes were used. The meat subset included 60 observations from 11 publications, representing 548 goats; there were 116 observations from 25 publications with 1,851 goats in the dairy subset; and the indigenous subset had 157 observations from 34 publications and 1,024 goats. Dairy and indigenous subsets were split into two groups-one for equation development and a second for evaluation. Observations with residuals greater than 1.5 times the residual SD from initial regressions were deleted. Equations were meat: MEI = 457.0 (SE = 22.3) + (25.23 (SE = 1.74) x ADG) (n = 57; R2 = 0.79); dairy goats (development subset, n = 63): MEI = 573.7 (SE = 46.2) + (23.56 (SE = 3.10) x ADG) (n = 56; R2 = 0.52); and indigenous (development subset, n = 87): MEI = 500.0 (SE = 11.9) + (18.59 (SE = 1.64) x ADG) (n = 76; R2 = 0.63). Intercepts and slopes from regressions of observed against predicted MEI with evaluation subsets based on dairy and indigenous equations were not different from 0 and 1, respectively. Prediction equations for the three biotypes had similar slopes, but the intercept for dairy differed (P < 0.05) from those for meat and indigenous. A common slope equation with a dummy variable (D; dairy = 1 and others = 0) was: MEI = 480.0 (SE = 13.5) + (103.2 (SE = 17.4) x D1) + (22.85 (SE = 1.23) x ADG) (n = 189; R2 = 0.74). In conclusion, based on a compiled database from publications with growing goats, MEm was 583.2 kJ/BW0.75 (139 kcal/kg BW0.75) for dairy goats and 480.0 kJ/BW0.75 (115 kcal/kg BW0.75) for meat and indigenous goats, and MEg was 22.85 kJ/g (5.46 kcal/g). Supported by USDA project No. 9803092. A comparison of two heart rate monitoring systems for goats Heart rate (HR) holds promise as an indirect means of estimating energy expenditure by ruminants. Therefore, two monitoring systems were compared with different goat breeds, diets, and levels of intake. The CP-402 stationary biosignal preamplifier method (BA) of Sable Systems (Henderson, NV) was compared with the human S610 monitor (HM) of Polar (Woodbury, NY). Electrode signals for BA were adjusted and filtered, with less dependence on signal quality relative to HM, whereas measurement with HM was more frequent (1- vs 10.5-min intervals). Heart rate was measured over 48-h periods while goats consumed alfalfa hay or a high concentrate diet for BW maintenance and on d 3 and 4 of fasting. Six Spanish (36 ± 1.3 kg), 7/8 Boer (39 ± 4.4 kg), Angora (23 ± 4.0 kg), and Alpine (41 ± 6.3 kg) wethers, > 1.5 yr of age, were employed. Stick-on ECG electrodes, used for both methods, were attached to the chest just behind and slightly below the left elbow and at the base of the jugular groove on the right side of the neck. Overall HR means were similar between methods (50.5 ± 11.75 and 50.1 ± 11.81 for BA and HM, respectively). Intercepts and slopes of equations for regressions of mean observations with BA against those with HM were similar among breeds and between diets and levels of intake. Therefore, all observations for BA were regressed against those for HM: BA HR = 1.784 (SE = 1.626) + 0.972 (SE = 0.032) x HM HR (SE = 0.032) (n = 48; R2 = 0.954). Because the intercept was not different from zero, a final no-intercept regression was fitted: BA HR = 1.005 (SE = 0.007) x HM HR (n = 48; R2 = 0.998), with the slope not different from one. In conclusion, BA and HM appear equally effective for measuring HR of goats in confinement, but the small size and light weight of HM may be appropriate for use in grazing goats. Metabolizable protein requirements of lactating goats Data from 31 studies with 174 treatment mean observations from goats in different stages of lactation were used to determine the metabolizable protein (MP) requirement for lactation (MPl). Milk protein yield (MkP) was calculated from milk yield and protein concentration. The MP supply, the sum of digestible ruminally undegraded dietary and microbial true protein, was estimated from ingredient composition and a database of CP degradability properties and ruminal fermentable energy concentration derived from literature values when not provided in the original publication. MPl was estimated from MP by subtracting MP used for maintenance functions (scurf (g CP), 0.2 x kg BW0.6; endogenous urinary (g CP), 1.031 x kg BW0.75; metabolic fecal (CP), 2.67% DM intake; 67% efficiency of use) and adjusting for BW change (14.3% protein). MPl was regressed against MkP, and after removing observations with residuals greater than 1.5 times the residual SD, the refitted equation was: MPl = 10.2 (SE = 8.13) + 1.18 (SE = 0.095) x MkP (n = 149, adjusted R2 = 0.51); the intercept was not different from zero (P > 0.05). Based on a no-intercept equation, 1.30 (SE = 0.034) g of MPl were required for 1 g of MkP, corresponding to milk protein efficiency of 0.77. In conclusion, these results suggest an MPl requirement for goats of 1.30 g/g of MkP. Although this approach and estimate of the MPl requirement should have utility in expressing needs for protein and(or) predicting milk production by lactating goats, improvements in accuracy from refined assumptions are desirable and will likely occur with future research. Supported by USDA project No. 9803092. Effects of ad libitum consumption of concentrate and forage offered separately or mixed on
growth of Alpine doelings Forty-four weaned Alpine doelings (16 ± 0.19 kg initial BW) were used in a 16-wk experiment to determine how separate free-choice offering of concentrate (C) and forage (F; wheat hay, 14.2% CP and 34.1% ADF) affect performance compared with consumption of mixed diets of different proportions of C and F. Treatments (two groups/treatment) were A-25C: 25% C mixed diet consumed ad libitum; A-50C: 50% C mixed diet consumed ad libitum; A-75C: 75% C mixed diet consumed ad libitum; A-C:A-F: ad libitum consumption of C and F, offered separately; and L-C:A-F: restricted intake of C (approximately 1.5% BW) and ad libitum intake of F. Orts averaged 6.7 ± 0.58% of diet offered. Intake of DM was similar among treatments (625, 641, 623, 704, and 653 g/d; SE = 38.6); dietary concentrate was 26, 53, 80, 84, and 61% of DM intake for A-25C, A-50C, A-75C, A-C:A-F, and L-C:A-F, respectively; SE = 1.51). Average daily gain was greatest (P < 0.05) for A-C:A-F and lowest (P < 0.05) for A-25C (53, 71, 81, 105, and 73 g; SE = 5.2), and ADG:DM intake ranked (P < 0.05) A-25C < A-50C and L-C:A-F < A-75C < A-C:A-F (85, 110, 130, 149, and 111 g/kg for A-25C, A-50C, A-75C, A-C:A-F, and L-C:A-F, respectively; SE = 5.2). In conclusion, separate free-choice offering of C and F for Alpine doelings appears promising as a simple means of achieving high ADG and efficient feed utilization, and restricted offering of C with separate free access to F can yield ADG and ADG:DM intake similar to ad libitum consumption of a mixed diet providing a comparable dietary concentrate level. Effects of method of offering broiler litter and level of prairie hay intake on growth of Boer
x Spanish wethers Thirty-four Boer x Spanish wethers (18 ± 0.3 kg initial BW) were used in a 12-wk experiment (2 x 2 + 1 factorial arrangement of treatments) to determine effects of ad libitum consumption of broiler litter (B) alone or mixed with corn (60% B; BC) and of ad libitum vs restricted (R) prairie hay (H) intake on feed intake and growth performance. Treatments were ad libitum H + an average of 22 g/d of mineral/vitamin supplement (Control, C); ad libitum H and B (AH-B); ad libitum H and BC (AH-BC); intake of 1% BW (DM) of H + ad libitum B (RH-B); and 1% BW of H + ad libitum BC (RH-BC). Hay DM intake averaged 494, 442, 336, 175, and 160 g/d (SE = 16.7), and total DM intake was 516, 700, 782, 474, and 585 g/d (SE = 26.2) for C, AH-B, AH-BC, RH-B, and RH-BC, respectively. Overall ADG ranked (P < 0.05) AH-BC > AH-B and RH-BC > C and RH-B (-6, 34, 79, 3, and 50 g); the ratio of ADG:DM intake ranked (P < 0.05) AH-BC and RH-BC > AH-B > C and RH-B (-13, 49, 97, 5, and 85 g/kg) for C, AH-B, AH-BC, RH-B, and RH-BC, respectively. In summary, offering B alone free-choice increased ADG by Boer cross goats when consuming H ad libitum but not with H intake restricted to 1% BW. The lower ADG:DM intake ratio for AH-B vs RH-BC indicates less efficient utilization of H than corn, although similar ADG reflects compensation via greater H intake. Mixing corn with B increased ADG similarly with both ad libitum and restricted H intake. In conclusion, depending on production goals and availability of high-quality feedstuffs such as cereal grains, free-choice consumption of B may be a simple and useful method of supplementing low-quality forage. Prediction of endogenous urinary nitrogen of goats J. Luo1, A. L. Goetsch1, J. E. Moore2, Z. B. Johnson3, T. Sahlu1, C. L. Ferrell4, M. L. Galyean5,
and F. N. Owens6 Three databases were constructed to estimate endogenous urinary nitrogen (EUN) in nonlactating and lactating goats. The first database consisted of 22 observations of direct measurement of EUN with low-N diets. A log-log weighted linear regression of EUN (g) on BW (kg) indicated that 0.75 was the most appropriate power of BW on which to express EUN. The second database, with 186 treatment mean observations for nonlactating goats, was split into a development set (n = 121) and a set for evaluation (n = 65). With the development set, urinary N (UN; g/kg BW0.75) was regressed on total N intake (TNI; g/kg BW0.75) and apparent digestible N intake (DNI; g/kg BW0.75). After removing outliers from the development set, equations validated with the evaluation set were: UN = 0.092 + (0.288 x TNI) [n = 79; R2 = 0.59] and UN = 0.165 + (0.340 x DNI) [n = 79; R2 = 0.59]. At 0 DNI, truly digestible N intake should equal metabolic fecal N; thus, the DNI estimate of EUN may be most appropriate for nonlactating goats with above maintenance feed intake. Prediction equations for lactating goats with above maintenance feed intake were: UN = 0.182 + (0.235 x TNI) [n = 33; R2 = 0.65] and UN = 0.160 + (0.354 x DNI) [n = 52; R2 = 0.72]. In summary, based on databases constructed from publications on goat feeding and nutrition, EUN of nonlactating goats with feed intake above maintenance was 0.165 g/kg BW0.75; EUN of lactating goats appeared similar to that for nonlactating goats. Maintenance energy needs of goats: predictions based on observations of heat and
recovered energyJ. Luo1, A. L. Goetsch1, I.V. Nsahlai1,2, Z. B. Johnson3, T. Sahlu1, J. E. Moore4, C. L. Ferrell5, M.
L. Galyean6, and F. N. Owens7 A database including 80 treatment means based on energy balance publications was constructed and analyzed to estimate fasting heat production (FHP) and ME required for maintenance (MEm) of goats. Experiments entailed comparative slaughter, respiration calorimetry, or CO2 entry rate techniques. Goats were of eight breeds and five physiological states (preweaning, growing, mature and nonlactating, early and mid-pregnancy, and lactating). Assuming that heat increment was 40% of total heat energy, unweighted and weighted (number of observations per treatment mean) log-log regressions (n = 74 following removal of outliers) of FHP against BW resulted in FHP (kJ) = 299 x BW0.762 (R2 = 0.82) and 244 x BW0.826 (R2 = 0.75), respectively. The 0.762 and 0.826 BW scaling factors did not differ (P > 0.17) from 0.75. Consequently, equivalent expressions based on mean BW were 311 to 314 kJ/kg BW0.75 and from regressions with a fixed BW exponent of 0.75 were 330 - 332 kJ/kg BW0.75. The slope and intercept of a regression of recovered energy (RE) against ME intake (MEI) for preweaning goats differed (P < 0.01) from those for other physiological states. A linear regression analysis of RE on MEI (both kJ/kg BW0.75) was conducted for the remaining 71 observations, after removing two observations with greater than 2.5 residual SD. The resultant equation was: RE = -298.0 (SE = 22.38) + (0.691 (SE = 0.028) x MEI) [n = 69; R2 = 0.90]. These estimates of FHP and efficiency of ME use yielded an estimate of MEm of 431 kJ/kg BW0.75. In summary, BW0.75 appeared acceptable as a scaler for expressing goat energy requirements, and FHP and MEm of 298 and 431 kJ/kg BW0.75, respectively, appear appropriate as general descriptors of the maintenance energy need of goats. Metabolizable energy requirements of lactating goats I. V. Nsahlai1,2, A. L. Goetsch1, J. Luo1, Z. B. Johnson3, J. E. Moore4, T. Sahlu1, C. L. Ferrell5, M.
L. Galyean6, and F. N. Owens7 Data from 44 studies with 243 treatment mean observations, representing 2,476 goats in various stages of lactation, were used to estimate the requirement and efficiency of use of ME for milk production. Development and evaluation data subsets comprised, respectively, 68 and 32% of observations. Intake of ME was adjusted for level of feed intake, as 1 - [0.018 x (L - 1)], with L = multiple of the ME requirement for maintenance. ME intake was also adjusted for energy lost in excretion of excess nitrogenous compounds in urine (ExUN), as 33.01 kJ/g of N intake above endogenous urinary N (0.165 g/kg BW0.75). Adjusted ME intake was partitioned into that used for maintenance [315 kJ/(kg BW0.75 km), where km or efficiency of ME use for maintenance = 0.503 + (0.019 x ME, MJ/kg DM)], ME secreted in milk, and ME gained as BW. When BW increased, ME intake was adjusted for tissue accretion (efficiency = 0.75) to derive dietary ME used in milk secretion. Milk yield was corrected to 4% fat [4%FCM; MJ/kg = 1.4694 + (0.4025 x % milk fat)]. For does decreasing in BW, FCM and milk energy from the diet were obtained by adjusting for use of mobilized tissue energy (23.9 kJ/kg; efficiency = 0.84). Based on no-intercept regressions, the dietary ME requirement for lactation was 5,493 (SE = 95.7) and 5,318 (SE = 106.0) kJ/kg FCM and efficiency of dietary ME utilization for lactation (ME regressed against milk energy) was 0.59 and 0.61 without and with correction for ExUN, respectively. Scatter plots of residuals with the development data subset, and intercepts and slopes that were not different from 0 and 1, respectively, from regressions with the evaluation data subset of observed against predicted FCM and milk energy from the diet, indicated acceptable accuracy and no obvious bias. Therefore, these estimates and this factorial approach seem useful to predict energy requirements of lactating goats, with potential for future enhancements based on research concerning assumptions used in deriving these values. Rotational grazing as a parasite management tool for goats W. E. Pomroy1,2, S. P. Hart1, and B. R. Min1 This study investigated the use of a short-duration, long-rest-period rotational grazing system as a method for controlling internal parasites in goats. Pastures (in central Oklahoma) were blocked by presence (15% cover) or absence of trees with two 2.0-ha pastures of degraded tallgrass native prairie per block. Two pastures were each divided with electric fence into 14 strips for rotational grazing beginning in May. Goats grazed each strip for 5 d and were moved to the next strip for two rotations, resulting in a 65-d rest period. Two pastures were set-stocked. Non-lactating, mature goats were used, six Angora and six Spanish does per pasture. Does were dewormed at the start of the study and fecal egg counts were used to confirm the efficacy of deworming. Initial and final weights of goats were taken. Tracer animals were dewormed effectively (confirmed by fecal egg counts) and allowed to graze with animals in each pasture (three tracers per pasture) for 17 d near the end of the study to measure pasture contamination. Tracers were euthanized after an additional 11 d and worms in the abomasum and small intestine were identified and counted. Goats were sampled every 3 wk for fecal egg counts (modified McMaster procedure) and hematocrit. Fecal egg counts were log transformed prior to statistical analysis. Fecal egg counts were reduced by rotational grazing (P < 0.05; 309 vs 121 eggs/g). There was a significant treatment by block effect (P < 0.005) in that pastures with trees had higher fecal egg counts, presumably due to animals congregating under trees and feces being shaded from the sun. Hematocrit and BW gain were not affected by treatment (P > 0.10). Pasture contamination with Haemonchus contortus larvae, (74.4% of worms identified) as determined by tracer animals, was lower (P < 0.001; 630 vs 40 worms per animal) for rotationally grazed animals than for set-stocked animals with a block by pasture interaction (P < 0.001) due to trees as previously discussed. Contamination by other species (Ostertagia circumcinta, 8.2% and Trichostrongylus colubriformis, 17.4%) of larvae followed a similar pattern. A short-duration, long-rest-period, rotational grazing system on tallgrass native range can effectively control internal parasites in goats, but the presence of trees in pastures can increase parasite infestation. Titration of efficacy of ivermectin and moxidectin against an ivermectin-resistant
Haemonchus contortus derived from goats in the field The objective of this study was to titrate the efficacy of ivermectin (IVM) and moxidectin (MOX) dewormers using variable dose rates of both anthelmintics against an IVM-resistant isolate of Haemonchus contortus. Yearling wether goats (45 kg BW, mean fecal strongylid egg count >1000 eggs/g) were randomly allocated to groups of 6 animals. Each group was treated as follows: I1 (IVM 0.1 mg/kg), I2 (IVM 0.2 mg/kg), I3 (IVM 0.4 mg/kg), I4 (IVM 0.8 mg/kg), M1 (MOX 0.05 mg/kg), M2 (MOX 0.1 mg/kg), M3 (MOX 0.2 mg/kg), M4 (MOX 0.5 mg/kg) and an untreated control group. The injectable cattle formulation of IVM and the pour on cattle formulation of MOX were both administered orally. Fecal egg counts (FEC) were estimated by a modified McMaster technique on the day of treatment (d 0) and d 7 and d 15 after treatment. Feces from each treatment group were cultured to determine the genera of larvae. Data were analyzed non-parametrically using a Kruskal-Wallis test. Haemonchus was the dominant genus found in pretreatment and control larval cultures but both Trichostrongylus and Ostertagia were also present in low numbers. Control group mean FEC varied by < 2% over the 3 sampling days. The percent reduction in FEC from pretreatment numbers was <80% for all dose rates of IVM, whereas the efficacy for M2, M3 and M4 were > 98% but the reduction for M1 was 93% on d 7 and 82% on d 15. On d 7 and 15 only the FEC of the 3 higher dose rates of MOX were significantly (P<.05) lower than the control group. Trichostrongylus were found to comprise 19% of control cultures, and 10%, 16%, 4%, and 22% of I1, I2, I3, and M1 cultures, respectively on d 7. Results indicate that IVM-resistance is present in H. contortus at IVM doses as high as 0.8 mg/kg but a dose as low as 0.1 mg/kg of the formulation of MOX used was effective. The survival of Trichostrongylus at 0.4 mg IVM/kg suggests the emergence of IVM resistance in this parasite as well. Adjustment factors for fat, protein, and somatic cell count for goat milk using different
species-specific calibration standards Currently, test-day samples of dairy goat milk are analyzed for fat, protein, and somatic cell count with laboratory equipment calibrated for cow milk, even though research has demonstrated that these measures are biased. The objective of this research was to examine breed, parity, and stage of lactation effects on this bias and to develop appropriate adjustment factors. Langston Dairy Herd Improvement (DHI) laboratory equipment was calibrated using both cow and goat milk standards. During 2001, 3,110 test-day samples from 875 does of six different breeds and 84 herds were analyzed for milk fat, protein, and somatic cell count with both calibrations. Of the 875 doe records, 373 were first parity, 181 second parity, 140 third parity, and 174 fourth or greater parity; and 196 were Alpine, 161 LaMancha, 284 Nubian, 45 Oberhasli, 124 Saanen, and 65 Toggenburg. Lactation was divided into 6 stages of 50 days according to days in milk (DIM). Differences (DIFF) in standards (cow vs goat) were analyzed as a repeated measures design using mixed model analysis. The statistical model included doe identity, breed, parity and stage of lactation with doe identity nested within breed as a random effect. There was no effect (P > 0.10) of breed or parity, on DIFF for fat, protein or somatic cell count. Stage of lactation affected (P < 0.01) DIFF for protein but not for fat or somatic cell count. Test-day samples analyzed with goat standards were regressed on test-day samples analyzed with cow standards to obtain adjustment factors. Multiplicative adjustments factors (cow standards adjusted to goat standards) were 1.027 for fat (R2 = 0.85), 1.164 for protein with DIM less than or equal to 100 d (R2 = 0.94), 1.125 for protein with DIM greater than 100 d (R2 = 0.99), and 0.937 for somatic cell count (R2 = 0.96). It appears that the bias in goat test-day samples analyzed under conventional DHI laboratory procedures can easily be alleviated using simple adjustment factors. The effect of diet on milk production, lactation curve, composition, and processing
characteristics in dairy goats This study investigated effects of different levels of concentrate supplementation on milk production (MP), composition, and processing characteristics (PC) with dairy goats grazing from April 2000 to September 2001. Forty-four Alpine goats (54 ± 10 kg BW) were randomly allocated to four treatments and supplemented with 0.66 (A and B), 0.33 (C), or 0 kg concentrate (D) per kg of milk over 1.5 kg/d. Mixed vegetative forages were rotationally grazed except for A (confined and fed alfalfa hay). The MP was recorded daily and milk samples were collected twice monthly and analyzed for fat (F), protein (P), lactose (L), solids-not-fat (SNF), total solids (TS), and PC (Year 2001 only). Egyptian Domiati cheese yield and organoleptic PC were analyzed fresh or after 1 or 2 mo pickling in whey solution. The lactation curve was calculated by Wood's incomplete gamma function. Average MP (kg/d) increased (R2 = 0.59; y = 1.72 x + 1.51; P < 0.001) with increasing level of concentrate supplementation. Average MP during both years was 3.7, 3.3, 3.3, and 2.8 kg/d for A, B, C, and D, respectively (P < 0.01). Initial MP and the rate of increase to the peak were similar among treatments, but the mean date of peak MP for D (29 d) was earlier (P < 0.05) than for A, B, and C (43, 35, and 36 d, respectively). Persistency was not affected (6.2) by treatment in 2001, but for D (5.6) was lower than for A, B, and C in 2000 (6.5, 6.2, and 6.1, respectively). Milk F concentration was similar among treatments; however, milk P and L concentrations for D were lower than for A, B, and C (P < 0.01). Average milk concentrations of F, SNF, TS, P, and L decreased linearly (P < 0.01) as lactation progressed. Cheese yield was 17% higher (P < 0.01) for B at the beginning and end of lactation than for other groups. Greatest cheese flavor was for D during summer (June-July; P < 0.01). In conclusion, MP, composition, and PC, as well as the lactation curve, were affected by the feeding treatment and stage of lactation. Effect of forage condensed tannins on gastro-intestinal parasite infection in grazing wether
goats The objective of this study was to evaluate effects of dietary condensed tannins (CT) in Sericea lespedeza (SL; Lespedeza cuneata; 4.6% extractable CT/kg DM) on total fecal egg output (TFEO; eggs/d) and stage of larvae development compared with non-CT-containing forage (rye/crabgrass (RC); 0.6 g extractable CT/kg DM) in grazing wether goats. A grazing trial (cross over) involving 11 naturally parasite-infected (>1,200 eggs/g) goats (47 ± 3.3 BW) were randomly selected 1 mo after Ivermectin treatment (0.2 mg/kg BW) failure. Larval culture of pre-treatment feces showed that 86-97% of larvae were Haemoncus, with the remainder being Trichostrognylus and Ostertagia. Periods lasted 15 d, with fecal samples taken on d 0, 5, and 15. The number of eggs/g feces were determined by a modification of the McMaster technique. Larvae were cultured for 10 d at 27oC by placing 20 g of fresh feces inside a small glass container within a larger container holding free water (20 ml) to maximize humidity. Larvae were collected using a modified Baermann's procedure and counted. Mean fecal egg counts (2,722 vs 1,162 eggs/g) and TFEO (173 vs 45 x 104 eggs/d) were lower (P < 0.01) for RC vs SL. Larvae development from eggs to infective stage of larvae (L3) by 15 d was 88% (3,432 vs 421 larvael/20 g feces; P < 0.001) lower for RC vs SL. In conclusion, CT in forages such as SL may reduce pasture contamination with infective larvae and be a valuable tool for parasite control. Tannins for suppression of internal parasites B. R. Min1, S. P. Hart1, and T. N. Barry2 Condensed tannins (CT) have biological effects that may aid in the control of dewormer-resistant internal parasites (IP). It is increasingly evident that control programs based on dewormers are failing to control IP as dewormer resistance has become more prevalent. Thus, alternative IP control strategies are necessary. The CT in forages have potential to be a component of IP control programs. The CT bind proteins and other molecules tightly at near neutral pH, such as occurs in the rumen, with dissociation in the acidic pH of the abomasum, freeing them for digestion. Effects of CT on parasitism can be assessed by grazing ruminants on forages that contain different levels of CT but otherwise are of similar nutritive value. Plant CT may have direct or indirect effects on IP. Direct effects might be mediated through CT-nematode interactions affecting physiological functioning of IP. Recently, in vitro and in vivo studies have shown that CT in several temperate and tropical forages (Hedysarum coronarium, Onobrychis viciifolia, Lotus pedunculatus, L. corniculatus, Lespedeza cuneata, and Quebracho CT) can inhibit infective gut worm larvae of sheep and goats and both gut and lung worms in farmed deer, with effects influenced by both concentration and structure of CT. Furthermore, preliminary research showed a 57% reduction in fecal egg counts (2,722 vs 1,162 eggs/g) and a 74% reduction in total fecal egg output (173 vs 45 x 104 eggs/d) in goats consuming forage Sericea lespedeza (4.6% extractable CT/kg DM) compared with rye/crabgrass. Indirectly, CT can improve protein nutrition by binding to plant proteins in the rumen and preventing microbial degradation, thereby increasing amino acid flow to the duodenum. Several ovine studies have shown that improved protein nutrition reduces parasite infestation. This is assumed to be mediated by enhanced host immunity, which may be especially important with selection for immunity to IP. In conclusion, CT in forages may have potential to aid in the control of IP. The effect of diet on somatic cell count, mastitis and gastro-intestinal parasite infestation in dairy goats. B. R. Min1, G. Tomita1, S. P. Hart1, W. Pomroy2, and T. Sahlu1 A study was conducted to investigate effects of concentrate level on milk somatic cell counts (SCC), incidence of intramammary infection (IMI) in udder halves, and gastro-intestinal parasite infestation in pastured dairy goats during mid- and late lactation (June-Sept., 2001; 90-200 days in milk). Twenty-four Alpine goats (55 ± 11 kg BW) were randomly allocated to four treatments and were supplemented with 0.66 (treatments A and B), 0.33 (treatment C), or 0 kg concentrate (treatment D) per kg of milk over 1.5 kg/d. Mixed vegetative forages (wheat/berseem clover, sudan grass, and cowpeas) were rotationally grazed except for A (confined and fed alfalfa hay). Milk samples for bacteriology and SCC were collected monthly from both halves. Fecal and blood samples were collected monthly for strongyloid fecal egg count (FEC) and packed cell volume (PCV) analysis, respectively. Prior to analysis, FEC and SCC were log transformed and PCV were transformed to their arcsin value. Coagulase negative Staphylococcus (52.4%), S. aureus (14.3%), and Pseudomonas aeruginosa (14.3%) were the most prevalent isolates. Infected glands had higher SCC (3.1 x 106 vs 1.0 x 106; P < 0.001) than uninfected glands. Mastitis was positively correlated with SCC in A (R2 = 0.41; P < 0.01) and B (R2 = 0.35; P < 0.05), but was not correlated with C (R2 = 0.18) or D (R2 = 0.29; P = 0.07). Infection increased SCC, but the degree of increase in SCC varied with pathogen. The FEC was lower in A (102 eggs/g; P < 0.01) than in B (972 eggs/g), C (972 eggs/g), and D (1,171 eggs/g), but there were no differences among levels of supplementation in pastured goats. Treatment D tended (P = 0.09) to have lowest PCV. High levels of concentrate supplementation did not reduce parasitism in pastured does. In addition, effective mastitis screening requires bacteriological culture since SCC were not highly correlated with IMI. Effect of pasture feeding and lactation stage on the biochemical composition of goat milk and cheese flavor K. A. Soryal, S. Zeng, B. Min, S. Hart, K. Tesfai, and T. Sahlu This study was to examine the effect of pasture feeding with different levels of concentrate and lactation stage on milk fatty acids and cheese characteristics. Twenty lactating Alpine goats were randomly assigned into four groups. Group A was confined, fed alfalfa hay and supplemented with 0.66 kg concentrate (per 1 kg of milk over 1.5 kg/day) (Control). The three pasture groups with different levels of concentrate were B (0.66 kg/d), C (0.33 kg/d), and D (no supplementation). Two batches of milk (10 kg) were collected monthly for processing into a soft cheese, Egyptian Domiati, from April through September 2001. Milk samples were analyzed for fat, protein, lactose, and TS, and cheese samples were organoleptically scored. Results indicated that the overall mean values of short chain (C6, C8, C10; SCFA) and long chain (C12, C14, C16, C18, C18:1, C18:2, and C18:3; LCFA) fatty acids in milk were 0.98 and 6.79 mg/g, respectively. Both SCFA and LCFA contents in goat milk were affected (P < 0.001) by stage of lactation. SCFA concentration for D was lower, 0.83 mg/g than for A, B, and C (1.04, 1.02, and 1.04 mg/g, respectively). However, LCFA content in B (7.34 mg/g) was higher (P < 0.05) than in D (6.28 mg/g). SCFA (1.7 mg/g) and LCFA (9.2 mg/g) in the early lactation were greater (P < 0.001) than in mid- to late lactation (0.7-1.2 and 6.0-8.1 mg/g, respectively). Milk fat content was positively correlated with milk protein (r = 0.42, P < 0.01), TS (r =0.87, P < 0.001), and cheese yield (r = 0.60; P < 0.001) but was negatively correlated with flavor score (r = -0.33; P < 0.01). Milk protein was positively correlated with TS (r = 0.68, P < 0.001) and cheese yield (r = 0.38; P < 0.05). SCFA and LCFA concentrations in milk were positively correlated (r = 0.7; P < 0.001). In conclusion, the best cheese flavor was obtained with milk from groups receiving little or no supplemented concentrate (C and D) in mid-lactation when LCFA and TS contents in milk were low. Goat milk constituents and processing characteristics with different feeding systems K. A. Soryal, S. S. Zeng, S. P. Hart, B. R. Min, B. Bah, R. Puchala, and T. Sahlu Pasture production of goat milk is being studied to reduce production cost and improve production viability of small family farms. The present work focused on effect of some feeding treatments on milk composition and processing characteristics during a whole lactation. This study included four feeding treatments: 1) conventional confinement system with alfalfa hay feeding and 0.66 kg concentrate / kg milk/d; 2) high level of concentrate (0.66 kg/kg milk) with grazing; 3) medium level of concentrate (0.33 kg/kg milk) with grazing; and 4) no concentrate supplementation, pasture alone. Milk samples of 5 Alpine goats from each treatment group were collected twice monthly from April to September 2001 and analyzed for major and minor constituents. Two batches of milk from each treatment group were collected at the same times for processing into soft cheese, Egyptian Domiati. Cheese samples were organoleptically scored and chemically analyzed for major and minor constituents, when fresh or after 1 or 2 months of pickling in whey solution. Fat, protein, and total solids of milk were higher (P < 0.01) for treatment 2 (3.46, 3.07, and 11.22%, respectively) compared with other treatments (3.11, 3.00, and 10.82%; 3.20, 3.05, and 10.93%; 3.22, 2.83, and10.56% for treatments 1, 3, and 4, respectively). Fat and total solids showed higher values at the last month of lactation (3.78 and 11.45, respectively) than those of other months (P < 0.10). Somatic cell counts was highest (P < 0.05) among goats in treatment group 2 and 3 (3.06 and 3.04 million/mL, respectively) and did not differ during lactation. Total organoleptic score of fresh cheese was not affected by treatment. The highest cheese flavor was detected for treatment 4 during June and July (P < 0.01), whereas body and texture of cheese was not influenced by feeding treatment at any time. Cheese yield was highest ( P < 0.01) for treatment 2 at the beginning and end of lactation 16.97 and 16.61%, respectively). In conclusion, the composition of goat milk and the quality of Domiati cheese were affected by the feeding treatment and stage of lactation. Effect of supplemental protein source on performance of Spanish x Boer wethers S. A. Soto-Navarro, A. L. Goetsch, T. Sahlu, and R. Puchala Fifty weaned Spanish x Boer wethers goats (27 ± 4.0 kg initial BW and 6.5 to 7.5 mo of age) were used in an experiment with 5 x 2 factorial arrangement of treatments to determine effects on growth of five sources (blood, corn gluten, feather, fish, and soybean meals) of ruminally undegraded intake protein (UIP) in 70% concentrate diets. Diets were formulated to be 13 or 19% CP and similar in UIP and the ratio of ruminally degraded intake protein to TDN within protein level. Ad libitum DM intake in the 27-wk experiment (1,043, 1,089, 1,153, 1,086, and 1,112 g/day; SE = 74.4) and ADG (136, 134, 143, 145, and 138 g for blood , corn gluten, feather, fish, and soybean meals, respectively; SE = 9.8) were similar between CP levels and among UIP sources. The ADG:DM intake ratio over the entire 27-wk period was similar among treatments. However, in the first 18 wk the ratio was greater (P < 0.05) for fish meal than for corn gluten, feather, and soybean meals (138, 1216, 124, 154, and 127 g/kg for blood, corn gluten, feather, fish, and soybean meals, respectively; SE = 8.3). In summary, with a dietary concentrate level of 70% and at least 13% CP, differences in amino acid profiles among blood, corn gluten, feather, fish, and soybean meals did not impact the rate or efficiency of growth by weaned Boer x Spanish wethers in a 27-wk period. However, fish meal improved efficiency of growth in the first 18 wk relatively to corn gluten, feather, and soybean meals. Effects of ruminally protected betaine and choline on performance of lactating Alpine goats T. Shenkoru1, F. N. Owens2, R. Puchala1, A. L. Goetsch1, and T. Sahlu1 Twenty-four Alpine does and 24 doelings were used to evaluate effects of dietary supplementing a 50% concentrate diet with protein or ruminally protected betaine or choline on milk yield and composition. Diets containing 15% CP (DM basis) were supplemented with 3% ruminally protected betaine (B), 3% ruminally protected choline (C), no added methyl donors (N), or feedstuffs high in ruminally undegradable protein to increase CP to 18% (H). Six animals, 3 doelings and 3 does, were allocated to each treatment and fed for ad libitum consumption. Doelings gained more weight (P < 0.05; 80 vs 15 g/d) but produced less milk (P < 0.05; 2.11 vs 3.24 kg/d) than does. Treatments had no effect on body weight gain by does or doelings (P > 0.10). Does fed H and B diets had higher DM intake than does fed N or C (P < 0.05; 2.13, 2.51, 2.24, and 2.49 kg/d); whereas, doelings consumed greater amounts of B and C (P < 0.05; 2.15, 2.68, 2.46, and 1.98 kg/d for N, B, C, and H, respectively). Treatments had no effect on milk production by doelings (2.08, 2.01, 2.18, and 2.15 kg/d) but B decreased milk production by does (P < 0.05; 3.45, 2.68, 3.27, and 3.54 kg/d for N, B, C, and H, respectively). Betaine decreased milk protein yield (P < 0.05; 82.7, 68.6, 80.1, and 83.8 g/d) and supplements decreased milk fat yield (P < 0.05; 83.5, 70.4, 71.8, and 72.1 g/d). Treatments had no effect on plasma NEFA or insulin in does, although B and C increased (P < 0.05) plasma NEFA and insulin in doelings. In summary, the lack of effect of additional protein in the diet indicates that protein status with 15% dietary CP was adequate. Betaine and choline altered plasma concentrations of some blood metabolites but did not improve milk production or body weight gain. Influence of dietary protein level on plasma insulin concentration, subcutaneous adipose tissue lipid content and composition in Boer cross and Spanish goats E. N. Ponnampalam1, R. Puchala1, V. Banskalieva1, L. J. Dawson2, T. Sahlu1, and A. L. Goetsch1 Effects of CP level on plasma insulin concentration and s.c. adipose tissue lipid content and composition were examined in Boer cross (BC) and Spanish (SP) goats. Twenty-three BC and 22 SP wethers (4 - 4.5 mo of age; 17.6 and 19.4 kg BW, respectively) were allocated to four dietary treatments. Consumed DM averaged 10, 14, 18, and 23% CP (T1, T2, T3, and T4, respectively). Feed intake was ad libitum and the experiment was 12 wk in length. In wk 11, blood samples were collected 4 h post-feeding for insulin determination. In wk 12, s.c. adipose tissue was biopsied between the ribs 12 and 13 for the determination of lipid content and composition. Diets did not influence DMI or ADG; ADG was 76, 86, 82, and 96 g for T1, T2, T3, and T4, respectively. However, ADG was greater (P < 0.01) for BC than for SP (97 vs 74 g). Dietary protein level did not alter plasma insulin (47.7, 40.2, 39.2, and 39.8 U/mL, respectively), although BC had a lower (P < 0.05) level than SP (36.2 vs 47.3 U/mL, respectively). Total s.c. tissue lipid content was highest (P < 0.01) among treatments for T1 (82.9, 72.5, 71.1, and 70.9%, respectively). Boer cross goats tended (P < 0.08) to have a lower total tissue lipid level (72.6 vs 76.0%) and a higher (P < 0.06) concentration of tissue phospholipids (2.8 vs 1.6%) than SP goats. Goats fed T2 and T4 tended to have a higher (P < 0.08) tissue phospholipid content than those fed T1 and T3 (3.3, 2.8, 1.3, and 1.5%, respectively). Even though T3 and T4 had more CP than recommended for a fast growth rate, they reduced s.c. adipose fat content without increasing ADG. The greater tissue phospholipid content for BC vs SP goats may be associated with increased growth rate, reduced s.c. tissue lipid content, and altered energy metabolism, as phospholipids play a major role in cellular metabolism and functions of membrane proteins. |
Extension Activities | Research Activities | Other Activities Library Activities | Quiz | Search | About Us | Contact Us | Faculty & Staff Research Extension Home | Top of Page Copyright© 2000 Langston University • Agricultural Research and Extension Programs P.O. Box 730 • Langston, OK 73050 • Phone 405.466.3836 |
