R.C. Merkel

ASAS Centennial Paper: Impact of animal science research on United States goat production and predictions for the future

Goat research in the United States has increased but at a rate less than that in production. Research on goat meat includes nutritional quality, packaging, color, sensory characteristics, and preslaughter management. Goat skins have value for leather, but quality of goat leather has not been extensively studied. Research in the production, quality, antibiotic residues, and sensory characteristics of goat milk and its products has aided development of the US dairy goat industry. Limited progress has been made in genetic improvement of milk or meat production. There is need to explore applications of genomics and proteomics and improve consistency in texture and functionality of goat cheeses. New goat meat and milk products are needed to increase demand and meet the diverse tastes of the American public. Despite research progress in control of mohair and cashmere growth, erratic prices and sale of raw materials have contributed to further declines in US production. Innovative and cooperative ventures are needed for profit sharing up to the consumer level. Internal parasites pose the greatest challenge to goat production in humid areas largely because of anthelmintic resistance. Study of alternative controls is required, including immunity enhancement via nutrition, vaccination, pasture management such as co-grazing with cattle, and genetic resistance. Similarly, the importance of health management is increasing related in part to a lack of effective vaccines for many diseases. Nutrition research should address requirements for vitamins and minerals, efficiencies of protein utilization, adjusting energy requirements for nutritional plane, acclimatization, and grazing conditions, feed intake prediction, and management practices for rapid-growth production systems. Moreover, efficient technology transfer methods are needed to disseminate current knowledge and that gained in future research.

Effects of breed and diet on growth and body composition of crossbred Boer and Spanish wether goats.

Sixty growing 3/4 Boer x 1/4 Spanish (BS) and Spanish (SP) wethers were used to determine influences of diet and breed on growth and body composition. A pelleted 50% concentrate diet (CD) and a diet based on grass hay (HD) were fed for ad libitum intake. Six wethers of each breed were slaughtered at 0 wk (total of 12). Six wethers of each diet-breed combination were slaughtered at 14 and 28 wk (24 per time) after consumption of the CD or HD. Initial BW of fed wethers were 21.6 and 18.8 kg for BS and SP, respectively (SEM = 0.7). Average daily gain during the entire experiment was influenced by an interaction (P < 0.05) between breed and diet (199, 142, 44, and 50 g/d for BS:CD, SP:CD, BS:HD, and SP:HD, respectively). Carcass mass was greater (P < 0.05) for CD vs. HD (56.2, 56.2, 53.2, and 54.0% of empty BW for BS:CD, SP:CD, BS:HD, and SP:HD, respectively). Mass of the liver (2.11, 1.92, 2.00, and 1.98% of empty BW; SEM = 0.05) and gastrointestinal tract (5.50, 4.83, 8.43, and 8.36% of empty BW for BS:CD, SP:CD, BS:HD, and SP:HD, respectively; SEM = 0.16) tended (P < 0.07) to be influenced by an interaction between breed and diet. Mass of internal fat (12.2, 12.1, 3.4, and 3.4% empty BW for BS:CD, SP:CD, BS:HD, and SP:HD, respectively; SEM = 0.3) differed (P < 0.05) between diets. Energy in the carcass (320, 236, 87, and 79 MJ), noncarcass tissues (318, 237, 77, and 72 MJ), and empty body (638, 472, 164, and 150 MJ) ranked (P < 0.05) BS:CD > SP:CD > BS:HD and SP:HD. Empty body concentration of protein was 18.3, 17.5, 18.3, and 19.7% (SEM = 0.3) and of fat was 24.0, 23.4, 10.8, and 10.3% for BS:CD, SP:CD, BS:HD, and SP:HD, respectively (SEM = 0.6). Energy concentration in accreted tissue was 17.0, 18.7, 16.3, and 6.4 MJ/kg for CD:wk 1 to 14, CD:wk 15 to 28, HD:wk 1 to 14, and HD:wk 15 to 28, respectively (SEM = 1.4). In conclusion, relatively high growth potential of growing Boer crossbred goats with a moderate to high nutritional plane does not entail a penalty in realized growth when the nutritional plane is low. Body composition of growing Boer and Spanish goats is fairly similar regardless of growth rate. For growing meat goats other than with a prolonged limited nutritional plane, an average energy concentration in accreted tissue is 17.3 MJ/kg.

Effects of Length of Pasture Access on Energy Use by Growing Meat Goats

Abstract Berhan, T., Puchala, R., Sahlu, T., Merkel, R.C. and Goetsch, A.L. 2005. Effects of length of pasture access on energy use by growing meat goats. J. Appl. Anim. Res., 28: 1–7. Six Boer × Spanish wethers (21 ± 1.0 kg initial BWand 7 to 8 months of age) were used in two simultaneous 3x3 Latin squares to determine effects of different lengths of access to pasture with moderate to high mass of forage of high nutritive value on energy expenditure (EE), recovered energy (RE), metabolizable energy (ME) intake and grazing activities. Wethers grazed a 0.7 ha pasture of a mixture of cool season forages in the fall I winter period for 4 (12.00 to 16.00 h), 8 (08.00 to 16.00 h) or 24 h; 4 and 8 h wethers were confined as a group in an enclosed facility at other times. Periods were at least 18 d in length, with 4 d for total feces collection in bags, 2 d to measure heart rate (HR) and grazing behavior and 1 d without feed or water for assessing body composition from urea space and shrunk BW. EE was based on HR and the predetermined ratio of EE.HR for each wether, and ME intake was the sum of EE and RE. Forage DM mass was 1985, 2016, 1634 and 1000 kg/ha at the beginning of period 1 and end of periods 1, 2 and 3, respectively. Hand-plucked forage samples averaged 22% crude protein and 39% neutral detergent fiber (dry matter basis). EE was greatest (P < 0.05) for 24 h of pasture access (4.96, 5.13 and 6.19 MJ id; SE = 0.253), although RE was similar among treatments (0.88,2.16 and 1.57 MJ I d for 4, 8 and 12 h, respectively; SE = 0.361). Intake of ME was greater for 8 and 24 h vs 4 h (5.84, 7.30 and 7.76 MJI d for 4, 8 and 24 h, respectively; SE = 0.530). As length of pasture access increased, number of steps (2.51, 4.57 and 6.41 × 1000), time spent ruminating (4.42, 6.33 and 7.28 h) and time eating (3.77, 6.35 and 7.24 h) increased (P < 0.05) and idle time (15.81, 11.32 and 9.48 h) decreased (P < 0.05), whereas time lying was greater (P < 0.05) for 4 and 8 vs 24 h (8.39, 8.25 and 6.66 h for 4, 8 and 24 h, respectively; SE = 0.161). In conclusion, with moderate to high mass of forage of high nutritive value, limited pasture access of a minimal length could yield performance by growing meat goats at least comparable to that with continuous access.

Changes in Energy Expenditure by Meat Goats with Varying Levels of Feed Intake Near Maintenance and Below

Abstract Asmare, A., Puchala, R., Merkel, R.C., Sahlu, T. and Goetsch, A.L. 2006. Changes in energy expenditure by meat goats with varying levels of feed intake near maintenance and below. J. Appl. Anim. Res., 29: 81–89. Eleven yearling meat goat wethers (7/8 Boer and 1/8 Spanish) were used in a 16-week experiment to determine effects of different levels of nutrient restriction and a maintenance level of intake after a severe restriction on energy expenditure (EE). Dehydrated alfalfa pellets were fed throughout the experiment. During the first 4 weeks for adaptation, wethers were fed near maintenance. In weeks 5 to 10, six wethers were fed at approximately 60% of the maintenance level and in weeks 11 to 16 were again fed near maintenance (L-H). The other five wethers were fed at approximately 80 and 60% of maintenance in weeks 5 to 10 and 11 to 16, respectively (M-L). Body weight and EE were measured on the last day of most weeks, with EE determined from heart rate and the previously determined ratio of EE to heart rate for each wether. Body weight differed among weeks but not between treatments (41.0, 41.5, 39.7, 39.5, 38.0, 37.2, 38.0, 37.5, 37.8, 38.8 and 30.3 kg for L-H (SE=1.29) and 38.6, 38.2, 37.2, 37.2, 36.6, 35.0, 36.6, 36.7, 35.9, 35.7 and 36.9 kg (SE=1.41)for M-L in wk 4, 5, 6, 7, 9, 10, 11, 12, 13, 15 and 16, respectively). Energy expenditure, expressed relative to BW at the end of the adaptation period, was 362, 366, 322, 280, 262, 260, 259, 331, 331 and 335 kJ/kg BW0.75 (SE=11.4) for L-H and 342, 378, 306, 301, 282, 276, 288, 263, 253 and 254 kJ/kg BW0.75 (SE=14.8) for M-L in weeks 4, 5, 6, 7, 9, 10, 11, 12, 13 and 15, respectively. Retained or recovered energy was different (P<0.05) from 0 for L-H in weeks 4, 5, 6, 11, 12, 13 and 15(65, −101, −56, −14, 4, 6, 192, 120, 121 and 117 kJ/kg week 4 BW0.75; SE=15.7) and for M-H in weeks 4, 5, 9 and 10 (92, −47, 25, 29, 49, 55, −14, 11, 21 and 20 kJ/kg week 4 BW0.75in weeks 4, 5, 6, 7, 9, 10, 11, 12, 13 and 15, respectively; SE=17.3). In conclusion, meat goats can markedly reduce EE in response to limited feed intake, with nonlinear change as time advances.

Effects of different quality diets consumed continuously or after a lower quality diet on characteristics of growth of young Spanish goats

Spanish wether and doeling kids (4.5 months of age; 13.4 kg initial BW) were used to determine influences of different quality diets consumed continuously or after a lower quality diet on characteristics of growth. The experiment consisted of two 9-week periods. Diets were low quality forage (L, prairie hay supplemented with soybean meal), high quality forage (H, dehydrated alfalfa pellets) and 70% concentrate (C). Kids on two treatments consumed L in Period 1, with half switched to C and half to H in Period 2 (LC and LH, respectively). The CC treatment entailed C consumption in both periods, and HH kids were fed H in both periods. For HC, H was fed in Period 1 followed by C in Period 2. DM intake ranked (P<0.05) LC and LH<CC<HC and HH in Period 1 (502, 352, 386, 610 and 636 g per day) and CC and LC<LH, HC and HH in Period 2 (652, 621, 833, 808 and 836 g per day for CC, LC, LH, HC and HH, respectively). ADG was lowest among treatments (P<0.05) for LC and LH in Period 1 (78, 1, −1, 84 and 80 g per day) and was 53, 82, 112, 92 and 73 g per day in Period 2 for CC, LC, LH, HC and HH, respectively (S.E. = 11). Empty body fat concentration at the end of Period 1 was greatest for the C diet and lowest for L (P<0.05; 12.2, 6.4 and 9.0% for C, L and H, respectively), and protein concentration was greatest among treatments (P<0.05) for L (16.8, 20.1 and 18.1% for C, L and H, respectively). At the end of Period 2, empty body fat concentration was 22.0, 15.9, 14.4, 20.1 and 15.2% (S.E.=1.94), and protein concentration was 16.8, 16.9, 17.9, 16.5 and 17.6% (S.E.=0.35) for CC, LC, LH, HC and HH, respectively). In summary, kids on the L diet in Period 1 mobilized fat to accrete a small amount of protein. Continuous consumption of C resulted in high fat accretion relative to H in both periods. Consumption of H in Period 1 followed by C in Period 2 resulted in growth characteristics slightly different from those with continual intake of C, with a lower concentration of protein in accreted tissue for HC. The diet in Period 2 for kids previously consuming L did not markedly affect tissue accretion. In conclusion, the nature of the diet consumed by young Spanish goats can impact current and subsequent rate and composition of BW gain.

Effects of stage of lactation and dietary forage level on body composition of Alpine dairy goats.

Multiparous Alpine does (42) were used to determine how stage of lactation and dietary forage level affect body composition. The feeding and body composition portion of the study had a 2 x 3 factorial arrangement of treatments. Eighteen does were fed a 40% forage diet (40F) and 18 received a diet with 60% forage (60F) for approximately 2, 4, or 6 mo of lactation (59 +/- 1.3, 116 +/- 1.0, and 184 +/- 1.4 d, respectively), followed by determination of body composition (6 does per diet at each time of slaughter). Does were assigned sequentially to treatments as kidding occurred. The 60F diet had 20% more dehydrated alfalfa pellets than the 40F diet, with higher levels of corn and soybean meal and inclusion of supplemental fat in the 40F diet. Initial body composition measures were made with 6 other does a few days after kidding (0 mo; 4 +/- 0.6 d). Before parturition, does were fed a 50% concentrate diet free choice. Intake of dry matter was greater for 60F than for 40F, average daily gain tended to be affected by an interaction between diet and month (0, 24, 121, -61, 46, and 73 g), and 4% fat-corrected milk was less in mo 5 to 6 than earlier. Internal fat mass was greatest among times at 6 mo and greater for 40F than for 60F. Mass of the gastrointestinal tract was less for 40F than for 60F and decreased with increasing time in lactation. Concentrations of fat in the carcass (13.8, 13.1, 16.5, 11.2, 11.5, and 14.4%), noncarcass tissues (18.6, 24.2, 33.3, 14.3, 16.5, and 24.5%), and empty body (16.5, 18.7, 25.2, 12.9, 14.1, and 19.5% for 40F at 2 mo, 40F at 4 mo, 40F at 6 mo, 60F at 2 mo, 60F at 4 mo, and 60F at 6 mo, respectively) were affected by stage of lactation and diet. Based on daily change in tissue mass and energy, energy concentration in tissue mobilized or accreted was 16, 20, and 32 MJ/kg in 1 to 2, 3 to 4, and 5 to 6 mo of lactation, respectively. In conclusion, based on tissue mass, more energy was expended by the gastrointestinal tract with 60F than with 40F. Considerable internal fat appeared to be mobilized in early lactation, particularly with the diet moderate to high in forage, with more rapid and a greater magnitude of repletion by does consuming the diet lower in forage. The concentration of energy in tissue mobilized or accreted varied with stage of lactation, being considerably greater at 5 to 6 mo of lactation than earlier.

Effects of Pasture Inclusion of Mimosa on Growth by Sheep and Goats Co-Grazing Grass/Forb Pastures

Abstract Animut, G., Goetsch, A.L., Aiken, G.E., Puchala, R., Detweiler, G., Krehbiel, C.R., Merkel, R.C., Sahlu, T. and Dawson, L.J. 2007. Effects of pasture inclusion of mimosa on growth by sheep and goats co-grazing grass/forb pastures. J. Appl. Anim. Res., 31: 1–10. Effects of mimosa alley-cropped in grass/forb pastures on growth performance of co-grazing sheep and goat wethers were determined. Eighteen sheep (Katahdin) and eighteen goats (≥75% Boer blood), with BW of 22±0.3 and 21±0.2 kg, respectively, and age of 4 to 5 months were used. Wethers grazed 0.4-ha pastures of grasses andforbs for 16 weeks. Three pastures with alley-cropped mimosa (W) and three without (WO) were divided into four paddocks for 2-week rotational grazing. Based on mimosa leaf mass at the beginning of grazing periods and animal days, daily consumption of mimosa leaf DM averaged 47 g per animal, although mimosa leaf harvest was complete long before the end of the grazing periods. Mimosa leaf samples averaged 2.81, 37.8, and 85.9% N, NDF and in vitro true DM digestibility (IVDMD), respectively. Forage mass (grass and forbs) was similar between treatments before (2928 and 2695 kg/ha) and after grazing (1507 and 1452 kg/ha) for WO and W, respectively. Pre-grazed forage concentrations of N (1.25 and 1.24%), NDF (64.5 and 63.8%) and IVDMD (52.9 and 56.2%) for WO and W, respectively, were similar between treatments, as was also true post- grazing. ADG was numerically greater (P=0.17) for W vs. WO (70 vs. 51 g/d; SE=7.7). In summary, alley-cropped mimosa increased nutritive value of the forage available for consumption. Nonetheless, mimosa had limited effect on growth performance of co-grazing sheep and goats perhaps because of decreasing mimosa leaf availability as 2-week grazing periods advanced or overall relatively low intake of mimosa leaf.

Relationships Between Body Composition and Shrunk Body Weight and Urea Space in Growing Goats

Abstract Wuliji, T., Goetsch, A.L., Puchala, R., Sahlu, T., Merkel, R.C, Detweiler, G., Soto-Navarro, S., Luo, J. and Shenkoru, T. 2003. Relationships between body composition and shrunk body weight and urea space in growing goats. J. Appl. Anim. Res., 23: 1–24. Growing Spanish wethers and doelings (31; 3.5 mo) consumed ad libitum diets differing in quality continuously for 18 wk or with an increase in quality after 9 wk. Urea space (US), shrunk body weight (SBW) and chemical composition of the whole body were determined at the beginning, middle and end of the experiment. In addition, at the beginning of the experiment the same determinations were made with two yearling Boer × Spanish doelings that had consumed a high quality diet ad libitum for 12 wk. Mean, standard error, minimum and maximum values were 20.4, 1.14, 10.3 and 42.0 kg SBW; 64.0, 1.05, 47.2 and 72.3% water; 15.7, 1.19, 6.0 and 32.3% fat and 17.3, 0.25, 14.0 and 20.9% protein. Regressions of water, fat and protein concentrations and masses against US and (or) SBW were performed. Model fit was assessed by R2, root mean square error (RMSE) and the distribution of residuals (observed—predicted) among predicted values. Overall, SBW explained considerably more variability in body composition than did US, although US slightly improved predictions of water and fat masses and concentrations. Equations explaining greatest variability with acceptable distributions of residuals were: water, kg = 1.274 (SE = 1.1608) + (0.1546 (SE = 0.05863) × US, kg) + (0.5782 (SE = 0.10861) × SBW, kg)—(0.0043 (SE = 0.00205) × SBW2, kg) [n = 33; R2 = 0.944; adjusted R2 = 0.938; RMSE = 2.266]; fat, kg = −0.921 (SE = 1.1389)—(0.1520 (SE = 0.05753) × US, kg) + (0.1564 (SE = 0.10656) × SBW, kg) + (0.0064 (SE = 0.00201) × SBW2, kg) [n = 33; R2 = 0.942; adjusted R2 = 0.936; RMSE = 0.734]; and protein,% water = 34.696 (SE = 3.9913)—(0.1175 (SE = 0.06192) × predicted water,%) [n = 33; R2 = 0.101; adjusted R2 = 0.073; RMSE = 1.983]. In conclusion, such equations may have utility for within experiment treatment comparisons or for assessing changes in composition. However, validation with an independent animal population is desirable as well as is future research with larger numbers of animals, different types of goats and procedural considerations.

Effects of Fertilization, Leguminous Trees, and Supplementation on Performance of Meat Goat Does and Their Kids Grazing Grass-Forb Pastures

ABSTRACT Thirty-nine Spanish does and their twin kids, approximately 4 wk old initially, were used in a 112-d experiment. Twelve grass-forb 0.4-ha pastures were subdivided into 4 paddocks and rotationally grazed for 2-wk periods in two 8-wk phases. Treatments were control, fertilization, mimosa, and supplementation, with 3 pastures per treatment. Three does with 6 kids grazed each of the control, supplementation, and mimosa pastures, and 4 does with 8 kids grazed fertilization pastures. Fertilization pastures received an application of N, P, and K 3 wk before the experiment, and supplementation animals received ad libitum access to a commercially available block containing 20% CP, with DM consumption averaging 116 g/d on a per doe basis. Mimosa leaf DM available at the beginning of each 2-wk period averaged 174 and 139 kg/ha in phase 1 and 2, respectively, although consumption was complete within the first few days of grazing periods. Fertilization increased prevalence of Bermudagrass at the beginning of grazing periods (23.2, 43.6, 20.3, and 28.2% before grazing and 63.5, 58.9, 42.9, and 55.7% after the experiment for control, fertilization, mimosa, and supplementation, respectively; SE =5.70). Forage DM mass (excluding mimosa leaf DM) was similar among treatments (1,491, 1,554, 1,386, and 1,430 kg/ha; SE = 69.0); the concentration of CP in hand-plucked forage samples was 12.9, 14.7, 14.3, and 13.1% for control, fertilization, mimosa, and supplementation, respectively (SE = 1.12). Doe ADG was similar among treatments (−55, −56, −29, and −59 g/d; SE = 10.9), and kid ADG was greater (P

Use of global positioning system collars to monitor spatial-temporal movements of co-grazing goats and sheep and their common guardian dog

Goats and sheep often graze together and guardian dogs are commonly used for protection from predators. The objective of this experiment was to characterise how goats, sheep and guardian dogs interact spatially when grazing the same pasture by use of global positioning system (GPS) collars as an unobtrusive means of behaviour monitoring. In 2002 and 2003, three meat goats and two sheep in a group of 12 of each species were randomly chosen and, along with a guard dog, fitted with GPS collars. Minimum distance travelled between consecutive 30-min fixes and distance between any two animals at the same fix time were calculated using spherical geometry. In 2002, the dog travelled the least between fixes during the day but more at night than either goats or sheep. However, in 2003, there was not a significant species difference in distance travelled in 24 h or during the day or night. All species travelled significantly more during day than night but none were stationary at night. Distance amongst goats and between sheep tended to be greater during day than night; distance between goats and sheep was greater than the distance amongst goats or between sheep. Hence, goats and sheep interacted as two separate entities rather than as one large herd/flock. Distance between the dog and goats was closer than between the dog and sheep, indicating a clear preference of the dog for goats that could relate to a difference in previous exposure to the two species. In summary, based on these findings protection by a guardian dog would be greater for a small group of goats than sheep and much greater than for a mixed species group. Or, with a large group of grazing animals, the number of dogs required for a certain level of protection would rank goats < sheep < mixture of goats and sheep.