T.A. Gipson

INVITED REVIEW: FEEDING BEHAVIOR OF GOATS

Factors influencing the feeding behavior of goats include grazing management practices, type of vegetation and season, breed and stage of production, group size, and properties of diets fed in confinement. Considerable information has been gathered from visual observation during daylight. However, tools are now available to characterize the feeding behavior of goats while grazing and while in confinement throughout the day. Global positioning system collars can be used to assess horizontal and vertical distances traveled, up or down position of the head, and movement within pasture or rangeland areas. A commercially available leg activity monitor allows estimation of the number of steps and time spent standing, lying, and moving rapidly without grazing. However, these measurements do not directly determine grazing. Therefore, prediction equations based on visual observation must be developed. Classification tree analysis is a robust method in developing these equations because the decision tree can be pruned or expanded to provide the best fit. Another equipment system determines time spent eating, ruminating, and remaining idle from the pattern of jaw movement. In addition to use of n-alkanes as internal markers to estimate digestibility, their profile can provide an indication of the botanical composition of the selected diet. Automated feeding systems for confined goats permit determinations such as number of feeder visits and meals, eating time, and rate and pattern of feed intake. Heart rate measured while goats are in normal production settings can be used to predict total energy expenditure through multiplication by energy expenditure per heartbeat of individual animals. To partition the activity energy cost, an estimate of ME intake or measures of changes in body energy status and milk energy yield are needed to determine other sources of heat to be subtracted from total energy expenditure. These methods create the opportunity to gain a fuller understanding of factors influencing the feeding behavior of goats and the relationships with levels and efficiencies of production.

A Conjugated Linoleic Acid Supplement Containing Trans-10, Cis-12 Conjugated Linoleic Acid Reduces Milk Fat Synthesis in Lactating Goats

The effect of conjugated linoleic acid (CLA) supplements containing trans-10, cis-12 for reducing milk fat synthesis has been well described in dairy cows and sheep. Studies on lactating goats, however, remain inconclusive. Therefore, the current study investigated the efficacy of a lipid-encapsulated trans-10, cis-12 CLA supplement (LE-CLA) on milk production and milk fatty acid profile in dairy goats. Thirty multiparous Alpine lactating goats in late lactation were used in a 3 x 3 Latin square design (14-d treatment periods separated by 14-d intervals). Does were fed a total mixed ration of Bermuda grass hay, dehydrated alfalfa pellets, and concentrate. Does were randomly allocated to 3 treatments: A) unsupplemented (control), B) supplemented with 30 g/d of LE-CLA (low dose; CLA-1), and C) supplemented with 60 g/d of LE-CLA (high dose; CLA-2). Milk yield, dry matter intake, and milk protein content and yield were unaffected by treatment. Compared with the control, milk fat yield was reduced 8% by the CLA-1 treatment and 21% by the CLA-2 treatment, with milk fat content reduced 5 and 18% by the CLA-1 and CLA-2 treatments, respectively. The reduction in milk fat yield was due to decreases in both de novo fatty acid synthesis and uptake of preformed fatty acids. Milk fat content of trans-10, cis-12 CLA was 0.03, 0.09, and 0.19 g/100 g of fatty acids for the control, CLA-1, and CLA-2 treatments, respectively. The transfer efficiency of trans-10, cis-12 CLA from the 2 levels of CLA supplement into milk fat was not different between treatments and averaged 1.85%. In conclusion, trans-10, cis-12 CLA reduced milk fat synthesis in lactating dairy goats in a manner similar to that observed for lactating dairy cows and dairy sheep. Dose-response comparisons, however, suggest that the degree of reduction in milk fat synthesis is less in dairy goats compared with dairy cows and dairy sheep.

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.

Determination of fetal numbers in Alpine does by real-time ultrasonography

Abstract Pregnancy diagnosis was carried out in Alpine does using a real-time ultrasound instrument equipped with a 5 MHz sector array probe. Eighty Alpine does were examined 5 and 7 wk after breeding. Does were restrained while standing, and the transducer probe was placed on the hairless caudal ventral abdominal wall cranial to the udder. Non-pregnant does were readily and accurately recognized at 5 and 7 wk after breeding. Number of fetuses per doe at 5 wk of gestation was different (P 0.2) to the number born. Accuracy for determining singles, twins, and triplets at 5 wk of gestation was 44, 73, and 67%, respectively; at 7 wk of gestation it was 82, 89 and 100%, respectively. This accuracy is similar to that reported in ewes. It was concluded that real-time ultrasonography scanning by the transabdominal route is a reliable method for early pregnancy diagnoses in goats. The technique also enables accurate separation of does carrying singles, twins, and triplets as early as 7 wk in gestation. Such information can be useful for improved nutritional management.

Energy expenditure and activity of different types of small ruminants grazing varying pastures in the summer.

Abstract Beker, A., Gipson, T.A., Puchala, R., Askar, A.R., Tesfai, K., Detweiler, G.D., Asmare, A. and Goetsch, A.L., 2009. Energy expenditure and activity of different types of small ruminants grazing varying pastures in the summer. J. Appl. Anim. Res., 37: 1–14. Objectives were to determine the activity energy cost for different types of goats as well as a breed of sheep and to evaluate methods of prediction. Eight animals each of yearling Angora, doeling goats, yearling Boer wether goats, yearling Spanish wether goats and Rambouillet wether sheep slightly more than 2 yr of age were used. Two animals of each type were randomly allocated to one of the four pastures 9.3, 12.3, 4.6 and 1.2 ha in area. Forage conditions varied markedly among pastures. The experiment was conducted in the summer with three periods, 30, 26 and 26 d in length. Energy expenditure (EE) was estimated from heart rate (HR) on pasture and EE:HR for each animal determined in a calorimetry system. A leg position/movement monitoring system and a GPS collar with position and movement sensors were used to estimate distance traveled and. time spent grazing/eating, resting while lying, resting while standing and walking without grazing/eating. EE attributable to activity (EEa%), expressed as a percentage of the ME requirement for maintenance plus activity in confinement, was determined based on total EE, BW and ADG. ADG was similar among animal types. Distance traveled was affected by an interaction (P<0.05) between animal type and period (Angora goats: 2.98, 2.33 and 2.47; Boer goats: 3.17, 3.46 and 2.68; Spanish goats: 2.85, 5.28 and 3.30; sheep: 3.04, 3.43 and 2.25 km in periods 1, 2 and 3, respectively (SE = 0.423). Time spent grazing was lowest among animal types (P<0.05) for Angora goats (4.3, 8.4, 7.8 and 6.8 h/day) and time spent walking without grazing was lower (P<0.05) for Angora goats and sheep than for Boer goats (1.7, 2.4, 2.1 and 1.2 h/day for Angora goats, Boer goats, Spanish goats and sheep, respectively). Total EE was affected by an interaction (P<0.05) between animal type and period (Angora, goats: 5.89, 5.55, and 5.16; Boer goats: 9.63, 10.92 and 8.55; Spanish goats: 6.73, 8.17 and 7.02; sheep: 12.54, 11.84 and 12.93 MJ/day in periods 1, 2, and 3, respectively (SE = 0.442). EEa% was affected by an interaction (P<0.05) between animal type and period (Angora goats: 15.7, 17.4 and 15.1; Boer goats: 59.7, 67.4 and 34.4; Spanish goats: 46.2, 61.7 and 41.6; sheep: 22.3, 11.8 and 21.9% in periods 1, 2 and 3, respectively (SE = 6.07). EEa% of goats was predicted with moderate accuracy (R2 = 0.40–0.41) and without bias from estimates of 5.79 and 5.05%/h spent grazing/eating and grazing/eating plus walking, respectively, determined in a companion experiment; however, these methods were not suitable for sheep.

Extended field test on the use of visual ear tags and electronic boluses for the identification of different goat breeds in the United States.

A total of 295 goats from 4 breeds (Alpine, n = 74; Angora, n = 75; Boer-cross, n = 73; Spanish, n = 73) were used to assess the retention of 3 types of electronic ruminal boluses (B1, 20 g, n = 95; B2, 75 g, n = 100; and B3, 82 g, n = 100) according to breed and feeding conditions. Time for bolus administration, reading with a handheld reader, and animal data recording (goat identification, breed, and bolus type) were registered. Each goat was also identified with 1 flag-button plastic ear tag (4.6 g, 51 x 41 mm). Retention of boluses and ear tags was regularly monitored for 1 yr. Ruminal fluid in 5 goats from each breed and management group was obtained with an oro-ruminal probe at 2 h after feeding. Ruminal pH was measured at 24 h and at wk 1, 2, 3, and 4 and used as an indicator of feeding conditions on rumen environment. Time for bolus administration differed by bolus type (B1, 14 +/- 2 s; B2, 24 +/- 2 s; B3, 27 +/- 2 s; P < 0.05) and goat breed (Alpine, 34 +/- 3 s; Angora, 17 +/- 2 s; Boer-cross, 16 +/- 1 s; Spanish, 19 +/- 2 s; P < 0.05), although differences were due to greater times for B2 and B3 in Alpine goats. Time for bolus administration averaged 22 +/- 1 s, and overall time for bolusing, reading, and data typing was 49 +/- 1 s on average. Ruminal pH differed according to breed and feeding management (lactating Alpine, 6.50 +/- 0.07; yearling Alpine, 6.73 +/- 0.07; Angora, 6.34 +/- 0.06; Boer-cross, 6.62 +/- 0.04; Spanish, 6.32 +/- 0.08; P < 0.05), but no early bolus losses occurred; rumen pH did not differ according to bolus type (B1, 6.45 +/- 0.05; B2, 6.39 +/- 0.07; B3, 6.49 +/- 0.05; P > 0.05). At 6 mo, electronic boluses showed greater retention than ear tags (99.7 vs. 97.2%; P < 0.05). At 12 mo, bolus retention was 96.3, 100, and 97.8% for B1, B2, and B3, respectively, not differing between B1 and B3 (P = 0.562). No effect of breed and bolus type on bolus retention was detected. No goat losing, at the same time, both bolus and ear tag was observed. Ear tag retention (91.7%) was less (P < 0.05) than all types of bolus (98.1%) on average. Ear tag retention in Boer-cross (98.6%) and Alpine (96.9%) goats was greater (P < 0.05) than in Spanish (88.7%) and Angora (82.9%) and tended to differ (P = 0.095) between Spanish and Alpine. In conclusion, unlike flag-button visual ear tags and mini-boluses used here, properly designed boluses (e.g., standard bolus) met International Committee for Animal Recording and National Animal Identification System retention requirements for goat identification under US conditions and are recommended in practice.

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 Stocking Rate, Breed and Stage of Production on Energy Expenditure and Activity of Meat Goat Does on Pasture

Abstract Beker, A., Gipson, T.A., Puchala, R., Askar, A.R., Tesfai, K., Detweiler, G.D., Asmare, A. and Goetsch, A.L. 2009. Effects of stocking rate, breed and stage of production on energy expenditure and activity of meat goat does on pasture. J. Appl. Anim. Res., 36: 159–174. Sixteen Boer and 16 Spanish multiparous does were used to determine how stocking rate (SR), breed and stage of production influence energy expenditure and behavioral activities on pasture and to develop a simple method of predicting energy used for activity. The experiment began in late spring at an average of 24 d after kidding. Litter size was two and kids were Boer and Spanish. Two does of each breed resided in eight 0.5-ha grass/forb pastures. There were five periods, 56, 60, 63, 64 and 73 d in length, corresponding to mid-lactation, early post-weaning, the late dry period, early gestation and mid-gestation. During period 1 and the first part of period 2, two additional does with kids of each breed grazed in four High SR pastures, with other pastures designated as Low SR. Because of low available forage mass in period 3, grass hay was offered for ad libitum consumption in periods 3–5 and a concentrate supplement was provided in periods 4 and 5. Energy expenditure (EE) was estimated from heart rate (HR) on pasture and EE.HR for each doe determined in a calorimetry system. A leg position I movement monitoring system and a GPS collar with position and movement sensors were used to estimate distance traveled and time spent grazing/eating, resting while lying, resting while standing and walking without grazing I eating. EE attributable to activity (EEa%), expressed as a percentage of the ME requirement for maintenance plus activity in confinement, was determined based on total EE, estimated milk production and doe BW and ADG. Forage DM mass in the middle of periods was 696, 246, 125 and 196 kg/ha for the High SR and 1362, 967, 479 and 610 kg/ha for the Low SR in periods 1, 2, 3 and 4, respectively. Kid ADG at weaning after 73 d was lower (P<0.05) for the High vs. Low SR (87 vs. 112 g). Distance traveled was not influenced by SR or breed but varied among periods (3.54, 3.76, 3.09, 3.08 and 4.10 km/d in periods 1, 2, 3, 4 and 5, respectively; SE = 0.193). Time spent grazing/eating tended (P < 0.07) to be greater for Boer vs. Spanish does (7.9 vs. 6.7 h/d) and differed among periods (8.0, 7.8, 7.6, 5.3 and 8.0 h I day in periods 1, 2, 3, 4 and 5, respectively; SE = 0.72). Total EE was greater (P <0.05) for Boer than for Spanish does (13.4 vs. 11.4 MJ/d) and differed among periods (13.5, 11.6, 11.7, 11.8 and 13.4 MJ I day in periods 1, 2, 3, 4 and 5, respectively; SE = 0.41). Likewise, predicted ME intake was greater (P<0.05) for Boer vs. Spanish does (14.2 vs. 12.2 MJ/d) and varied with period (16.1, 10.6, 12.8, 12.6 and 14.0 MJ/day in periods 1, 2, 3, 4 and 5, respectively; SE = 0.47). EEa% was not influenced by SR, breed or period, averaging 49%. Behavioral activities were not highly related to EEa%, although no-intercept regressions against time spent grazing/eating and grazing/eating plus walking indicated an increase in EEa% of 5.79 and 5.05%/h, respectively. In conclusion, although EEa% was not affected by trea tments of this experiment or highly related to behavioral activities monitored, it represents a sizeable cost of energy deserved of further study.

Effects of restricted feed intake on heat energy by different goat breeds.

Sixteen Boer goat doelings, 16 Spanish doelings, and 8 Angora doelings and 8 wethers, 283, 316, and 330 d of age initially (SEM = 5.0), respectively, were used to evaluate effects of nutrient restriction on heat energy (HE). During the first and second 10-wk phases, 8 animals of each breed were fed a 50% concentrate pelletized diet at a level adequate for maintenance and moderate energy accretion (CONT). Other animals were fed approximately 50% of these amounts in phase 1 relative to initial BW, followed by the greater level of feeding in phase 2 based on initial or actual BW when greater (REST). Average daily gain was 43, -20, 16, -78, 8, and -48 g in phase 1 (SEM = 5.0) and 26, 44, 50, 65, 27, and 32 g in phase 2 (SEM = 3.5) for Angora-CONT, Angora-REST, Boer-CONT, Boer-REST, Spanish-CONT, and Spanish-REST, respectively. Total HE was greater for CONT vs. REST in both phases (P < 0.001), greater in phase 1 for Angora than for Boer (P < 0.01) and Spanish (P < 0.01), and greatest (P < 0.01) in phase 2 among breeds for Angora [481, 347, 430, 356, 424, and 338 kJ/kg of BW(0.75) per day in phase 1 (SEM = 11.1), and 494, 479, 445, 397, 444, and 406 kJ/kg of BW(0.75) per day in phase 2 (SEM = 11.3) for Angora-CONT, Angora-REST, Boer-CONT, Boer-REST, Spanish-CONT, and Spanish-REST, respectively]. Equations describing the temporal pattern of HE (kJ/kg of BW(0.75) per day), expressed as a percentage of the wk-0 value and corrected for corresponding breed × week CONT means, in phase 1 were 95.8 ± 2.43 - (8.18 ± 1.144 × week) + (0.655 ± 0.1098 × week(2)) for Angora (R(2) = 0.58), 95.3 ± 2.63 - (4.34 ± 1.237 × wk) + (0.271 ± 0.1187 × wk(2)) for Boer (R(2) = 0.41), and 97.4 ± 2.21 - (4.69 ± 1.068 × wk) + (0.282 ± 0.1021 × wk(2)) for Spanish (R(2) = 0.53). Phase 2 equations were 78.9 ± 2.22 + (8.74 ± 1.036 × wk) - (0.608 ± 0.0095 × wk(2)) for Angora (R(2) = 0.60), 77.5 ± 2.10 + (3.30 ± 0.978 × wk) - (0.153 ± 0.0942 × wk(2)) for Boer (R(2) = 0.39), and 80.6 ± 2.50 + (4.50 ± 1.165 × wk) - (0.208 ± 0.1122 × wk(2)) for Spanish (R(2) = 0.43). These equations indicate that changes in HE in response to nutrient restriction and realimentation were more rapid and of greater magnitude in Angora vs. Boer and Spanish. The temporal pattern of decline in HE by Boer and Spanish during restriction was similar, but the subsequent rise with realimentation was slower and smaller for Boer. In conclusion, most appropriate methods of predicting change in the maintenance energy requirement during and after periods of limited feed intake may differ among breeds of goats.

Conditions to test electric fence additions to cattle barb wire fence for goat containment

Two experiments were conducted to determine appropriateness of conditions in a method being developed for evaluating efficacy of different electric fence additions to cattle barb wire fence for goat containment. In Experiment 1, two 6×6 Latin squares (LS), each with 24 yearling Boer goat doelings previously exposed to electric fence, were conducted. After overnight fasting, groups of four doelings were placed in 2.4×2.4 m pens without forage. One pen side was five strands of four-point barb wire (non-electrified) at 31, 56, 81, 107 and 132 cm from the ground adjacent to a pasture with abundant vegetation. One LS had periods 2–3 days in length and the other 7 days. Electric fence treatments for each square were addition to barb wire fence of four electric fence strands 15, 28, 43 and 58 cm from the ground at low voltage of 4–4.5 kV (4S-LV); two strands at 15 and 43 cm and high voltage of 8.5–9 kV (2S-HV); two strands at 15 and 43 cm and low voltage (2S-LV); one strand at 15 cm and low voltage (1S-LH-LV); one strand at 43 cm and low voltage (1S-HH-LV) and one strand at 23 cm and high voltage (1S-MH-HV). Percentages of doelings exiting (6% and 4%) and shocked in 2 h (15% and 16% for 7 and 2–3 days, respectively) were low and did not differ between period lengths. The percentage of doelings exiting in 2 h was not affected by fence treatment. Period of squares affected (p<0.05) the percentage of doelings shocked (54%, 25%, 4%, 6%, 0% and 4% for periods 1, 2, 3, 4, 5 and 6, respectively). Experiment 2 was with 30 Boer and 30 Spanish growing doelings in the same study area. Because of less than anticipated shock and exit in Experiment 1, some conditions were changed, including a defined period of exposure to electric fence, training for pen exit before the experiment and longer fasting (24 or 36 h). Fence treatments were those of Experiment 1 but without 4S-LV and with slightly lower voltage. Doelings were divided into three sets of 20 and used in a completely randomised design (CRD), and one set continued repeated exposure to the different fence treatments in a 5×5 LS. Thereafter, period 1 was repeated in period 6. For the CRD approach, the percentage of doelings exiting in 1 h was >90%. With the LS method the percentage of doelings exiting also was similar among fence treatments but was 75%, 70%, 40%, 70% and 75% for 2S-HV, 2S-LV, 1S-LH-LV, 1S-HH-LV and 1S-MH-HV, respectively. With a comparison involving doeling sets used in the LS, the percentage of doelings shocked was lower (p<0.05) in period 6 vs. 1 (5% vs. 50%), although there was no difference with doelings not used in the LS. In conclusion, results were not promising for successful use of an LS approach, and large differences between experiments in levels of shock and exit indicate need for further change in conditions.