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Abstract: Female Alpine goats, 18 approximately 17 months of age (yearling) and 18 approximately 5-month-old (growing), were used in an experiment to determine effects of animal age, urea dose (100, 130, and 160mg/kg BW), and time without feed and water (shrink; 0, 16, and 24h) on urea space (US) estimates. A 20% (w/v) urea solution was infused into a jugular vein, with blood sampled before infusion and every 3min to 21min. BW was 49.8, 47.4, and 47.0kg for yearlings and 26.1, 24.6, and 23.9kg for growing animals after 0, 16, and 24h shrinks, respectively (S.E.=0.80). Time of urea equilibration with body water, determined by a grafted polynomial quadratic–linear model, was affected by a dose×age×shrink interaction (P <0.05); yearling means did not differ (ranging from 7.3 to 10.8min), although those for growing animals were greater (P <0.05) for 0h:130mg (13.0min) and 24h:130mg (13.2min) compared with 24h:100mg (7.6min) and 16h:130mg (7.1min). Based on these times, 12-min samples were used to determine urea space. Urea space was influenced by an age×shrink interaction (P <0.05), being similar among shrink times for yearlings (17.8, 18.8, and 18.9kg) and greater (P <0.05) for growing animals after 0 than 24h shrink (12.9, 11.3, and 10.0kg for 0, 16, and 24h, respectively). Hemoglobin concentration in plasma, as an index of hemolysis, was lower (P <0.05) for growing than for yearling animals (1.16% versus 1.86%), lowest among doses (P <0.05) for 100mg (1.05, 1.74, and 1.75% for 100, 130, and 160mg, respectively), and highest among shrink times (P <0.05) for 24h (1.46, 1.42, and 1.61% for 0, 16, and 24h, respectively). In conclusion, effects of and interactions involving some of the factors studied and high variability in the time of urea equilibration with body water indicate that, regardless of the particular urea space procedures chosen, relatively high numbers of observations are warranted. [Copyright &y& Elsevier]

Abstract: Yearling Boer×Spanish goat wethers (40) were used to develop and compare body composition prediction equations for mature meat goats based on urea space (US) and body condition score (BCS). Before the experiment, one-half of the animals were managed to have high BW and BCS (1–5, with 1 being extremely thin and 5 very fat) and the others were managed to have low BW and BCS. During the 24-week experiment, initially fat wethers were fed to lose BW and BCS and initially thin wethers were fed to increase BW and BCS. BCS, US, and whole body chemical composition were determined after 0, 12, and 24weeks. Mean, minimum, and maximum values were 42.1 (S.E.=1.12), 24.5, and 59.0kg for shrunk BW; 3.0 (S.E.=0.11), 1.5, and 4.0 for BCS; 61.3 (S.E.=1.01), 53.7, and 76.5% for water; 20.2 (S.E.=1.11), 4.7, and 29.7% for fat; 15.6 (S.E.=0.19), 13.3, and 18.1% for protein; and 2.9 (S.E.=0.062), 2.2, and 3.7% for ash, respectively. For water, fat, and ash concentrations and mass, simplest equations explaining greatest variability (with independent variables of US, BCS, and (or) shrunk BW) based on BCS accounted for more variation than ones based on US, although in some cases differences were not large (i.e., water and ash concentrations and mass). Neither US nor BCS explained variability in protein concentration. Equations to predict protein mass based on shrunk BW and US or BCS were nearly identical in R 2 and the root mean square error. A 1unit change in BCS corresponded to change in full BW of 8.9kg (full BW (kg)=17.902+(8.9087×BCS); R 2 =0.653), fat concentration of 7.54% (%fat=−5.076+(7.5361×BCS); R 2 =0.612), and energy concentration of 3.01MJ/kg (energy (MJ/kg)=0.971+(3.0059×BCS); R 2 =0.615). In summary, BCS may be used as or more effectively to predict body composition of meat goats than US. The primary determinant of BCS, within the range of BCS observed in this experiment, was body fat content. [Copyright &y& Elsevier]

Abstract: Yearling Boer×Spanish goat wethers were used to assess effects of initial body condition and subsequent level of feed intake on body composition. Before the experiment, 21 wethers were fed to achieve high body condition score (BCS; 1 to 5, with 1=extremely thin and 5=extremely fat) and BW (initially fat; I-F) and 21 were fed for low BCS and BW (initially thin; I-T). During the experiment, I-F wethers were fed low amounts of a pelletized diet and I-T wethers received high amounts. Harvest measures were determined before the experiment (week 0) and after 12 and 24 weeks, with seven animals per initial body condition and time. BCS in Experiment 1 was 3.8, 3.2, 2.6, 1.9, 2.8, and 3.5 (S.E.=0.11) and live BW was 53.3, 46.2, 42.4, 36.6, 40.1, and 48.2kg (S.E.=2.03) for I-F:week 0, I-F:week 12, I-F:week 24, I-T:week 0, I-T:week 1, and I-T:week 2, respectively. There were substantial declines in mass of many internal organs with advancing time for I-F compared with relatively small change for I-T. Examples include the reticulo-rumen (1.03, 0.59, 0.52, 0.87, 0.78, and 0.73kg; S.E.=0.041), small intestine (0.59, 0.27, 0.23, 0.55, 0.33, and 0.36kg; S.E.=0.021), large intestine (0.40, 0.24, 0.24, 0.33, 0.33, and 0.26kg; S.E.=0.017), and liver (0.86, 0.45, 0.42, 0.56, 0.60, and 0.67kg for I-F:week 0, I-F:week 12, I-F:week 24, I-T:week 0, I-T:week 12, and I-T:week 24, respectively; S.E.=0.031). Conversely, change in internal or non-carcass fat mass was much greater for I-T versus I-F (5.7, 3.9, 2.8, 0.6, 2.5, and 5.1kg for I-F-week 0, I-F-week 12, I-F-week 24, I-T-week 0, I-T-week 12, and I-T-week 24, respectively; S.E.=0.33). Changes in carcass mass of protein (−5.9, −5.3, 7.0, and 5.8g/day; S.E.=0.89) and fat (−1.9, 0.2, 21.4, and 26.6g/day; S.E.=2.35) were greater (P <0.05) for I-T versus I-F, as was also true for non-carcass protein (6.1, 0.0, 14.5, and 6.3g/day; S.E.=0.91) and fat (−16.3, −10.4, 13.6, and 26.3g/day for I-F:weeks 1–12, I-F:weeks 1–24, I-T:weeks 1–12, and I-T:weeks 1–24, respectively; S.E.=2.49). Based on energy concentrations in empty body tissue lost or gained in weeks 1–12 and 1–24 (14.8, 12.1, 19.9, and 26.4MJ/kg for I-F:weeks 1–12, I-F:weeks 1–24, I-T:weeks 1–12, and I-T:weeks 1–24, respectively; S.E.=2.13), the energy concentration in weeks 13–24 was 9.4 and 32.9MJ/kg for I-F and I-T, respectively. In conclusion, the energy concentration in tissue mobilized or accreted by yearling meat goats within certain body condition ranges may not necessarily be the same and appears influenced by initial animal characteristics and subsequent feeding conditions. [Copyright &y& Elsevier]