A.L. Goetsch

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.

Dairy goat performance with different dietary concentrate levels in late lactation

Alpine yearling doelings (22; 44+/-1.0kg) and mature does (25; 59+/-1.7kg) were used in an experiment with 16 weeks in late lactation, 8-13 weeks dry and 12 weeks in the subsequent lactation. Diets of 20, 35, 50 or 65% concentrate and 2.18, 2.34, 2.49 and 2.62Mcal/kg ME, respectively (20C, 35C, 50C and 65C treatments, respectively), were consumed ad libitum in late lactation, with a 35% concentrate diet (2.18Mcal/kg ME) in the first 4 weeks of the dry phase and 50% concentrate (2.65Mcal/kg ME) until kidding. Other goats consuming 20 or 35% concentrate in late lactation received 65 (2.65Mcal/kg ME) or 50% concentrate, respectively, in the dry phase (20A and 35A treatments, respectively). All goats consumed a 50% concentrate diet (2.42Mcal/kg ME) in the subsequent early lactation. DM intake in late lactation was similar among treatments (1.95, 2.21, 2.17, 2.10, 1.99 and 2.00kg per day for 20C, 35C, 50C, 65C, 20A and 35A, respectively; S.E.=0.098) and greater (P<0.05) for does versus doelings (2.16 versus 1.98kg per day; S.E.=0.058); DM intake in the dry phase was similar among treatments. Relative to BW, DM intake was greater (P<0.05) for doelings than for does in late lactation (4.16 versus 3.43% BW) and early lactation (4.56 versus 3.80% BW). The effect of dietary treatment on milk production in late lactation varied with parity (P<0.05); milk production by doelings was 1.39, 1.49, 1.43, 1.57, 1.29 and 1.52kg per day and by does was 1.01, 1.89, 2.38, 1.63, 1.17 and 1.34kg per day for 20C, 35C, 50C, 65C, 20A and 35A, respectively; S.E.=0.200). BW change during the entire 16 weeks late lactation phase was greater (P<0.05) for 65C than for other treatments except 50C (6.9, 5.6, 9.1, 10.4, 5.8 and 4.0kg for 20C, 35C, 50C, 65C, 20A and 35A, respectively; S.E.=1.28), although BW at kidding and litter weight were similar among treatments. BW, DM intake and milk production in the first 12 weeks of the subsequent lactation were not affected by dietary treatment or parity. In conclusion, with moderate to high quality forage in late lactation and a moderate level of concentrate in the dry period, the level of concentrate fed in late lactation and in the dry period may not affect subsequent lactation performance regardless of parity. Milk production by doelings in late lactation appears relatively less responsive to dietary concentrate level than that by does.

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 dietary tallow level on performance of Alpine does in early lactation

Sixty Alpine does (initial BW 47+/-1.3kg) were used to determine effects of dietary inclusion of different levels of partially hydrogenated tallow on performance in early lactation (weeks 3-11). Treatments entailed a 30% concentrate, negative control (NC) diet and five diets higher in concentrate (42-46%) with 0, 1.5, 3.0, 4.5 or 6.0% DM of partially hydrogenated tallow (0T, 1.5T, 3.0T, 4.5T and 6.0T, respectively). DM intake was 1.54kg per day for the NC and 1.86, 1.80, 1.99, 2.17 and 1.96kg per day for the five tallow treatments, respectively, BW was similar among treatments and increased as the trial progressed (47.4, 48.4, 49.8, 50.4, 50.8 and 51.3kg at weeks 3, 5, 7, 9, 11 and 13, respectively). Milk yield was lower (P<0.05) for NC (2.61kg per day) compared with the mean of the other diets and changed quadratically (P<0.05) as tallow level increased (2.85, 3.08, 3.14, 3.21 and 2.69kg per day for the five tallow treatments, respectively). Milk fat concentration was lower (P<0.05) for NC (2.94%) than for the mean of other diets and increased linearly (P<0.05) with increasing tallow level (3.00, 3.17, 3.34, 3.48 and 3.58%) whereas, milk protein concentration was not affected by level of tallow (2.72, 2.80, 2.93, 2.85, 2.90 and 2.90% for NC, and the five tallow treatments, respectively). The estimated NE(l):4% fat-corrected milk yield ratio was 0.93Mcal/kg for NC and 1.30, 1.11, 1.21, 1.37 and 1.44Mcal/kg for the five tallow treatments, respectively. The results indicated that in Alpine does, milk yield in early lactation increased as dietary tallow level was increased to 3 and 4.5% but decreased when the level was increased to 6%, although milk fat concentration increased linearly and the protein level was unchanged. These results suggest beneficial usage by lactating Alpine does of low to moderate levels of partially hydrogenated tallow in diets moderate in concentrate level, although ingredient availability and costs will influence ultimate dietary ingredient decisions.

Effects of different management practices on preweaning and early postweaning growth of Alpine kids

Two sets of 40 dairy goat Alpine kids (3-9 days of age) were used to determine effects of group versus individual pens, preweaning access to forage and different milk feeding restriction regimens on preweaning and early postweaning growth. Treatments in the first experiment were: C1: individual pens; C2: two kids per pen; P: group pen; and PF: P plus free access to alfalfa hay. Treatment did not affect ADG gain in the 8-week preweaning phase (167, 173, 167 and 168g per day; S.E.=4.5) or in week 1-12 (137, 134, 149 and 128g per day for C1, C2, P and PF, respectively; S.E.=6.7). Treatments in the second experiment were: AL: ad libitum milk intake with two meals in week 3-8, then 50% of intake on the preceding few days with one meal in week 9-10; R-1X and R-2X: 75% of intake on the last few days of week 2 with one or two meals, respectively, in week 3-8, then, 50% intake with one meal in week 9-10; and R-2X-1X: 75% intake with two meals in week 3-6, then 37.5% intake with one meal in week 7-10. Milk DM intake in week 1-10 was greatest (P<0.05) among treatments for AL (174, 115, 128 and 113g per day for AL, R-2X, R-1X and R-2X-1X, respectively). Starter diet DM intake (g per day) was 51, 78, 72 and 143 in week 7-8 (S.E.=16); 138, 194, 165 and 249 in week 9-10 (S.E.=15); 343, 396, 388 and 417 in week 11-12 (S.E.=47); and 508, 530, 489 and 539 in week 13-14 (S.E.=38) for AL, R-2X, R-1X and R-2X-1X, respectively. ADG (g per day) was 139, 120, 119 and 131 in week 1-10 (S.E.=7) and 105, 109, 123 and 117 in week 11-14 (S.E.=16) for AL, R-2X, R-1X and R-2X-1X, respectively. In conclusion, although group pens and forage access may not enhance ADG of artificially reared dairy goat kids by promoting early dry feed consumption restricted feeding regimens can yield preweaning and early postweaning ADG comparable to ad libitum milk intake. Also, feeding milk in restricted amounts once daily appears feasible, and a second reduction in milk intake in the latter part of the suckling phase may further stimulate dry feed intake.

Effects of stage of lactation and dietary concentrate level on energy utilization by Alpine dairy goats

Twenty-four lactating and 13 nonlactating Alpine goats were used to determine effects of stage of lactation and dietary concentrate level on energy utilization. Diets comprising 60 or 20% concentrate (60%C and 20%C, respectively) were consumed ad libitum by lactating animals and at a level of intake near maintenance by nonlactating animals. Measurement periods were d 25 to 31 (early), 87 to 94 (mid), and 176 to 183 (late) of lactation. Eleven observations were made in early and mid lactation for each diet, and 8 and 7 were made in late lactation for the 60%C and 20%C diets, respectively. Efficiency of metabolizable energy (ME) use for maintenance (66.9, 71.4, and 61.1% for early, mid, and late lactation, respectively) and the maintenance ME requirement (479, 449, and 521 kJ/kg of BW(0.75) for early, mid, and late lactation, respectively) determined with nonlactating animals differed among stages of lactation. The efficiency of ME use for maintenance was similar between diets, but the maintenance requirement tended to be greater for the 60%C than for the 20%C diet (504 vs. 463 kJ/kg of BW(0.75)). The latter difference may have involved greater ME intake for the 60%C diet, resulting in a slightly greater difference between ME intake and total heat energy for the 60%C compared with the 20%C diet (11 vs. -8 kJ/kg of BW(0.75)). Intake of ME by lactating goats was greater for the 60%C than for the 20%C diet (18.6 vs. 16.3 MJ/d). Recovered energy in lactation from mobilized tissue tended to be greater for the 60%C than for the 20%C diet (8.44 vs. 6.55 MJ/d) and differed among stages of lactation (2.60, 1.59, and 1.13 MJ/d in early, mid, and late lactation, respectively). Recovered energy in tissue gain was similar among stages of lactation and between diets and was not different from 0. Efficiency of use of dietary ME for lactation differed among stages of lactation (59.5, 51.9, and 65.4% for early, mid, and late lactation, respectively) and tended to be greater for the 60%C than for the 20%C diet (64.2 vs. 54.9%). The efficiency of use of dietary ME for maintenance and lactation was similar among stages of lactation and was greater for the 60%C compared with the 20%C diet (64.3 vs. 60.9%). Predicted milk yield from National Research Council requirements was reasonably accurate. In conclusion, using data of nonlactating goats to study energy utilization for maintenance in lactation has limitations. Efficiency of energy use by lactating dairy goats consuming diets high in concentrate appears greater than that by goats consuming diets low in concentrate. Despite differences in nutrient requirement expressions, observations of this study support National Research Council recommendations of energy requirements of lactating dairy goats.

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.

Growth of Spanish, Boer×Angora and Boer×Spanish goat kids fed milk replacer

Seventy-seven male kids were used to compare growth performance of Spanish (S, n=26), BoerxAngora (BA, n=21) and BoerxSpanish (BS, n=30) kids during the preweaning period. All kids were removed from does 3 days postpartum, moved indoors and randomly allocated to individual cages. Kids received goat milk fortified with milk replacer for approximately 1 week followed by 600ml of milk replacer (23% CP, 30% crude fat) twice daily until weaning at 8 week. At 3 week of age, all kids had ad libitum access to a commercial goat starter diet (20% CP). Feed intake was measured daily and BW gain at 2-week intervals. There were interactions (P<0.05) between breed and time or 2-week period in BW, BW gain and feed efficiency. Boer crosses (i.e., BA and BS) were heavier than S kids at 2, 6 and 8 weeks of age (P<0.05), but there were no BW differences between Boer crosses (P0.10). From Week 3-8, Boer crosses gained BW more rapidly (P=0.001) than did S kids (60, 71 and 77g/day for S, BA and BS, respectively), although BW gain of S in Week 3-4 was greater (P<0.05) than that of Boer crosses (60, 50 and 54g/day for S, BA and BS, respectively). Starter diet DM intake in Week 3-8 was greatest for BS (S versus BA and BS, P=0.05; BA versus BS, P<0.01) (23, 24 and 37g/day for S, BA and BS, respectively). The ratio of BW gain to total DM intake in Week 3-8 was greater (P=0.03) for BA and BS than for S (0.52, 0.59 and 0.58 for S, BA and BS, respectively). The incidence of scours was 17, 21 and 31% for S, BA and BS kids, respectively (P0.10). These results reflect that crossbreeding with Boer goats can improve growth of young kids and, thus, potentially increase economic returns for goat producers.

Effects of different fresh-cut forages and their hays on feed intake, digestibility, heat production, and ruminal methane emission by Boer × Spanish goats1

Twenty-four yearling Boer × Spanish wethers were used to assess effects of different forages, either fresh (Exp. 1) or as hay (Exp. 2), on feed intake, digestibilities, heat production, and ruminal methane emission. Treatments were: 1) Sericea lespedeza (SER; Lespedeza cuneata), a legume high in condensed tannins (CT; 20% and 15% in fresh forage and hay, respectively), 2) SER supplemented with polyethylene glycol (SER-PEG; 25 g/d), 3) alfalfa (Medicago sativa), a legume low in CT (ALF), and 4) sorghum-sudangrass (Sorghum bicolor), a grass low in CT (GRASS). Experiments were 22 d, which included 16 d for acclimatization followed by a 6-d period for fecal and urine collection, and gas exchange measurement (last 2 d). Intake of OM was 867, 823, 694, and 691 g/d (SEM = 20.1) with fresh forage, and 806, 887, 681, and 607 g/d with hay for SER, SER-PEG, ALF, and GRASS, respectively (SEM = 46.6). Apparent total tract N digestion was greater for SER-PEG vs. SER (P < 0.001) with fresh forage (46.3%, 66.5%, 81.7%, and 73.2%; SEM = 1.71) and hay (49.7%, 71.4%, 65.4%, and 54.8% for SER, SER-PEG, ALF, and GRASS, respectively; SEM = 1.57). Intake of ME was similar among treatments with fresh forage (8.24, 8.06, 7.42, and 7.70 MJ/d; SEM = 0.434) and with hay was greater for SER-PEG than ALF (P < 0.03) and GRASS (P < 0.001) (8.63, 10.40, 8.15, and 6.74 MJ/d for SER, SER-PEG, ALF, and GRASS, respectively; SEM = 0.655). The number of ciliate protozoa in ruminal fluid was least for SER with fresh forage (P < 0.01) (9.8, 20.1, 21.0, and 33.6 × 10(5)/ml; SEM = 2.76) and hay (P < 0.02) (6.3, 11.4, 13.6, and 12.5 × 10(5)/ml for SER, SER-PEG, ALF, and GRASS, respectively; SEM = 1.43). Methane emission as a percentage of DE intake was lower (P < 0.01) for SER vs. ALF and GRASS with fresh forage (6.6, 8.3, 9.4, and 9.2%; SEM = 0.64) and hay (4.3, 4.9, 6.4, and 6.7% for SER, SER-PEG, ALF, and GRASS, respectively; SEM = 0.38). In summary, methane emission in this short-term experiment was similar between a legume and grass low in CT as fresh forage and hay. The CT in SER markedly decreased N digestibility and elicited a moderate decline in ruminal methane emission. Supplementation with PEG alleviated the effect of CT on N digestibility but not ruminal methane emission, presumably because of different modes of action. In conclusion, potential of using CT-containing forage as a means of decreasing ruminal methane emission requires further study, such as with longer feeding periods.

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.