Body Composition Of Lambs Research Articles

Estimating body composition using CT scans of cross-bred lambs fed at 2feeding levels and 2stages of maturity to inform predictive growth models.

Livestock producers would benefit from more precise predictions of the growth response from nutrients consumed. Previously published models are often limited by the realities of data collection and are unable to account for alterations to body composition, due in part to the response of visceral organs to an alternate diet. The computerized tomography (CT) scanning of lambs enables the analysis of changes in body composition of individual animals over time, potentially supporting better model development and testing. The aim of this experiment was to develop a repeatable method for the analysis of live lamb body composition using CT scans. A secondary aim was to compare the data collected from CT scanning during a feeding trial to 2 predictive lamb growth models. Cross-bred lambs were fed 2 feeding levels at 2 stages of maturity, with CT scans at the beginning and end of each 8-wk feeding period. The CT scan-derived values for body composition taken at the beginning of feeding periods were used as inputs for 2 existing lamb growth models. Predictions of body composition were compared with CT scan-derived values at the end of feeding periods. The CT scan analysis method used a proportion of images from each lamb to reduce manual image editing. The method was developed by comparing the estimated mass and volume of empty body components using all available CT scans to estimated values using a reduced number of scans from 12 lambs. The CT scan-derived lean tissue mass aligned with model predictions at the end of each feeding period, however, CT scan-derived fat mass was greater than predictions by both models especially for the high feeding level at the later stage of maturity. These results highlight that the analysis of body composition using CT scans requires further validation, particularly for the viscera, and that models likely require refinement to better predict the efficiency of energy utilization by different tissues. The use of live animal CT scans can provide more accurate predictions of the growth of saleable products than measuring liveweight alone and will enable ruminant growth models to better adapt to different genetics and changing diets than comparative slaughter. To replicate the current data using comparative slaughter would require 4 times the animals, as individual lambs were CT scanned 4 times in this study, demonstrating the potential value of CT scanning in live animal research.

Daily injection of the β2 adrenergic agonist clenbuterol improved poor muscle growth and body composition in lambs following heat stress-induced intrauterine growth restriction.

Background: Intrauterine growth restriction (IUGR) is associated with reduced β2 adrenergic sensitivity, which contributes to poor postnatal muscle growth. The objective of this study was to determine if stimulating β2 adrenergic activity postnatal would rescue deficits in muscle growth, body composition, and indicators of metabolic homeostasis in IUGR offspring. Methods: Time-mated ewes were housed at 40°C from day 40 to 95 of gestation to produce IUGR lambs. From birth, IUGR lambs received daily IM injections of 0.8μg/kg clenbuterol HCl (IUGR+CLEN; n = 11) or saline placebo (IUGR; n = 12). Placebo-injected controls (n = 13) were born to pair-fed thermoneutral ewes. Biometrics were assessed weekly and body composition was estimated by ultrasound and bioelectrical impedance analysis (BIA). Lambs were necropsied at 60days of age. Results: Bodyweights were lighter (p ≤ 0.05) for IUGR and IUGR+CLEN lambs than for controls at birth, day 30, and day 60. Average daily gain was less (p ≤ 0.05) for IUGR lambs than controls and was intermediate for IUGR+CLEN lambs. At day 58, BIA-estimated whole-body fat-free mass and ultrasound-estimated loin eye area were less (p ≤ 0.05) for IUGR but not IUGR+CLEN lambs than for controls. At necropsy, loin eye area and flexor digitorum superficialis muscles were smaller (p ≤ 0.05) for IUGR but not IUGR+CLEN lambs than for controls. Longissimus dorsi protein content was less (p ≤ 0.05) and fat-to-protein ratio was greater (p ≤ 0.05) for IUGR but not IUGR+CLEN lambs than for controls. Semitendinosus from IUGR lambs had less (p ≤ 0.05) β2 adrenoreceptor content, fewer (p ≤ 0.05) proliferating myoblasts, tended to have fewer (p = 0.08) differentiated myoblasts, and had smaller (p ≤ 0.05) muscle fibers than controls. Proliferating myoblasts and fiber size were recovered (p ≤ 0.05) in IUGR+CLEN lambs compared to IUGR lambs, but β2 adrenoreceptor content and differentiated myoblasts were not recovered. Semitendinosus lipid droplets were smaller (p ≤ 0.05) in size for IUGR lambs than for controls and were further reduced (p ≤ 0.05) in size for IUGR+CLEN lambs. Conclusion: These findings show that clenbuterol improved IUGR deficits in muscle growth and some metabolic parameters even without recovering the deficit in β2 adrenoreceptor content. We conclude that IUGR muscle remained responsive to β2 adrenergic stimulation postnatal, which may be a strategic target for improving muscle growth and body composition in IUGR-born offspring.

Validation of a mechanistic dynamic pre-weaned lamb growth and body composition simulation model

Lamb growth and body composition simulation models can provide valuable insights into the assessment of feeding regimens and rearing systems, allowing optimisation of farm profitability without the need for in-vivo trials. The objective of the present study was to evaluate the performance of a published mechanistic dynamic model on the growth and body composition of pre-weaned lambs using independently published data sets. Data generated from eight treatments, representing three artificial lamb rearing experiments (n = 77 lambs) were used. Initial body composition data were obtained from four lambs at approximately two days of age, with the remaining lambs being provided with defined nutritional treatments until the trial end-point. The body composition of lambs at slaughter was determined in six treatments across two experiments. Feed intake and live weight (LW) of lambs were recorded in all treatments. The LW, average daily gain (ADG) and ash deposition rates of lambs were accurately simulated by the model (paired t-test, P > 0.05). The overall empty body weight (EBW), gutfill, protein and fat deposition rates were overestimated, and water deposition rate was underestimated by the model (paired t-test, P < 0.05). Collectively, these results suggest that the model can be used at the farm level with acceptable accuracy to determine lamb growth. Further improvements in the model are required for protein, fat and water deposition rates, gutfill and EBW to make it more applicable for wider usage.

Effects of dietary energy density and supplemental rumen undegradable protein on intake, viscera, and carcass composition of lambs recovering from nutritional restriction.

Variation in nutrition is a key determinant of growth, body composition, and the ability of animals to perform to their genetic potential. Depending on the quality of feed available, animals may be able to overcome negative effects of prior nutritional restriction, increasing intake and rates of tissue gain, but full compensation may not occur. A 2 × 3 × 4 factorial serial slaughter study was conducted to examine the effects of prior nutritional restriction, dietary energy density, and supplemental rumen undegradable protein (RUP) on intake, growth, and body composition of lambs. After an initial slaughter (n = 8), 124 4-mo-old Merino cross wethers (28.4 ± 1.8 kg) were assigned to either restricted (LO, 500 g/d) or unrestricted (HI, 1500 g/d) intake of lucerne and oat pellets. After 8 wk, eight lambs/group were slaughtered and tissue weights and chemical composition were measured. Remaining lambs were randomly assigned to a factorial combination of dietary energy density (7.8, 9.2, and 10.7 MJ/kg DM) and supplemental RUP (0, 30, 60, and 90 g/d) and fed ad libitum for a 12- to 13-wk experimental period before slaughter and analysis. By week 3 of the experimental period, lambs fed the same level of energy had similar DMI (g/d) and MEI (MJ/d) (P > 0.05), regardless of prior level of nutrition. Restricted-refed (LO) lambs had higher rates of fat and protein gain than HI lambs (P < 0.05) but had similar visceral masses (P > 0.05). However, LO lambs were lighter and leaner at slaughter, with proportionally larger rumens and livers (P < 0.05). Tissue masses increased with increasing dietary energy density, as did DMI, energy and nitrogen (N) retention (% intake), and rates of protein and fat gain (P < 0.05). The liver increased proportionally with increasing dietary energy density and RUP (P < 0.05), but rumen size decreased relative to the empty body as dietary energy density increased (P < 0.05) and did not respond to RUP (P > 0.05). Fat deposition was greatest in lambs fed 60 g/d supplemental RUP (P < 0.05). However, lambs fed 90 g/d were as lean as lambs that did not receive supplement (P0, P > 0.05), with poorer nitrogen retention and proportionally heavier livers than P0 lambs (P < 0.05). In general, visceral protein was the first tissue to respond to increased intake during refeeding, followed by non-visceral protein and fat, highlighting the influence of differences in tissue response over time on animal performance and body composition.

Growth and Body Composition of Artificially-Reared Lambs Exposed to Three Different Rearing Regimens.

Simple SummaryOptimum lamb growth and cost-effective artificial lamb rearing are important to maximise farm profit. In addition to milk feeding, supplementation of a solid feed with balanced nutrients and an adequate level of fibre will aid rumen development, allowing for a smooth transition from a liquid to a solely solid diet. This study aimed to determine the effect of pellet fibre level, milk replacer composition and early milk weaning at 42 days of age, on the growth and body composition of lambs reared artificially to 57 days of age. Results demonstrate that lamb growth rate to 57 days of age was not affected by early weaning or pellet fibre level. Early milk weaning increased pellet intake and empty rumen weight. Early weaning resulted in leaner carcasses due to reduced fat deposition and lower total feed costs compared to lambs offered milk to 57 days of age. Overall, feeding lambs either low or high fibre pellets and weaning early (42 days of age) was shown to be beneficial, as growth was similar to unweaned lambs, but leaner carcasses and reduced feed costs were observed.This study was designed to investigate the influence of pellet fibre level, milk replacer composition and age at weaning on growth and body composition of lambs reared artificially. Romney ram lambs were randomly allocated to one of three rearing treatments; HFP57: commercial milk replacer to 57 days of age, and high fibre concentrate pellets; HFP42: commercial milk replacer with early weaning at 42 days of age, and high fibre concentrate pellets; LFP42: high protein milk replacer from 2–16 days of age followed by commercial milk replacer with early weaning at 42 days of age, and low fibre concentrate pellets. Lambs were slaughtered at 57 days of age. Overall average daily liveweight gain of lambs did not differ (p > 0.05) between treatments. Dressing out percentage, carcass weight, empty small intestine and omental fat were higher (p < 0.05) in HFP57 than in both HFP42 and LFP42 lambs. HFP42 and LFP42 lambs had heavier (p < 0.05) empty rumen weights. Whole body protein content was higher (p < 0.05) in HFP42 lambs compared to both HFP57 and LFP42 lambs. Fat content and daily fat deposition were greater (p < 0.05) in HFP57 lambs than HFP42 and LFP42 lambs. Weaning lambs at 42 days of age with provision of either low or high fibre concentrate pellets, resulted in similar growth rates, reduced whole body fat deposition and was a more cost-effective rearing regimen.

Evaluation of oral citrulline administration as a mitigation strategy for fescue toxicosis in sheep.

Gestating ewes consuming ergot alkaloids, from endophyte-infected (E+) tall fescue seed, suffer from intrauterine growth restriction and produce smaller lambs. Arginine (Arg) supplementation has been shown to increase birth weight and oral citrulline (Cit) administration is reported to increase arginine concentrations. Two experiments were conducted to: 1) evaluate if oral supplementation with Cit or water, to ewes consuming E+ fescue seed, increases lamb birth weight and 2) determine the effectiveness of Cit and citrulline:malate as an oral drench and elevating circulating levels of Cit to determine levels and dose frequency. In experiment 1, gestating Suffolk ewes (n = 10) were assigned to one of two treatments [oral drench of citrulline–malate 2:1 (CITM; 81 mg/kg/d of citrulline) or water (TOX)] to start on d 86 of gestation and continued until parturition. Ewes on CITM treatment had decreased (P < 0.05) plasma Arg and Cit concentrations during gestation. At birth, lambs from CITM ewes had reduced (P < 0.05) crude fat and total fat but did not differ (P > 0.05) in birth weight from lambs born to TOX ewes. In experiment 2, nonpregnant Suffolk ewes (n = 3) were assigned to either oral citrulline (CIT; 81 mg/kg/d), citrulline–malate 2:1 (CITM; 81 mg/kg/d of citrulline), or water (CON) drench in a Latin Square design for a treatment period of 4 d with a washout period of 3 d. On d 4, blood samples were collected at 0, 0.5, 1, 2, 3, 4, 6, 8, 10, 12, and 18 h post drench. Oral drenching of CIT and CITM increased (P < 0.0001) Cit concentrations within 2 h and levels remained elevated for 6 h. Apparent half-life of elimination for CIT and CITM were 8.484 and 10.392 h, respectively. Our results show that lamb birth weight was not altered with a single oral drench of citrulline–malate; however, lamb body composition was altered. The level and frequency of citrulline dosing may need to be greater in order to observe consistent elevation of Cit/Arg concentrations to determine its effectiveness in mitigating fescue toxicosis.

Prediction of lamb body composition using in vivo bioimpedance analysis

The objective of this study was to evaluate the potential of in vivo bioimpedance analysis (BIA) as a method to estimate body composition in lambs. Thirty-one Texel x Ile de France crossbreed ram lambs were slaughtered at pre-determined intervals of average weights of 20, 26, 32, and 38 kg. Before the slaughter of the animals, their body weight (BW) and body length (BL) were measured. The values for resistance (Rs) and reactance (Xc) were collected using a single-frequency BIA equipment (Model RJL Quantum II Bioelectrical Body Composition Analyzer). The BIA main variables such as body bioelectrical volume (V), phase angle (PA), resistive density (RsD), and reactive density (XcD) were then calculated. The soft tissue mass of the right-half cold carcass was analyzed in order to determine its chemical composition. Multiple regression analyses were performed using the lamb body composition as dependent variables and the measurements related to bioimpedance as independent variables. The best regression models were evaluated by cross-validation. The predictive model of moisture mass, which was developed by using XcD and V, accounted for 84% of its variation. Resulting models of percentage moisture (R2 = 0.79), percentage lean mass (R2 = 0.79), percentage fat (R2 = 0.79), and fat mass (R2 = 0.87) were obtained using RsD and V. Furthermore, the values of RsD regarding V, and PA in the prediction models accounted for 91% and 89% of variation in protein mass and lean mass, respectively. Bioimpedance analysis proved to be an efficient method to estimate the body composition of lambs slaughtered at different body mass stages.

Sire carcass breeding values affect body composition in lambs — 2. Effects on fat and bone weight and their distribution within the carcass as measured by computed tomography

This study assessed the effect of paternal Australian Sheep Breeding Values for post weaning c-site eye muscle depth (PEMD) and fat depth (PFAT), and post weaning weight (PWWT) on the composition of lamb carcasses. Composition was measured using computed tomography scans of 1665 lambs which were progeny of 85 Maternal, 115 Merino and 155 Terminal sires. Reducing sire PFAT decreased carcass fat weight by 4.8% and increased carcass bone by 1.3% per unit of PFAT (range 5.1mm). Increasing sire PEMD reduced carcass fat weight by 3.8% in Maternal and 2% in Terminal sired lambs per unit of PEMD (range 4.3 and 7.8mm), with no impact on bone. Increasing sire PWWT reduced carcass fat weight, but only at some experimental locations. Differences in composition varied between sire types with Maternal sired lambs having the most fat and Merino sired lambs the greatest bone weight. Genetic effects on fatness were greater than the environmental or production factor effects, with the converse true of bone.

Sire carcass breeding values affect body composition in lambs — 1. Effects on lean weight and its distribution within the carcass as measured by computed tomography

Data are obtained from computed tomography scanning of 1665 lambs at locations around Australia. Lambs were progeny of Terminal, Maternal and Merino sires with known Australian Sheep Breeding Values for post weaning c-site eye muscle depth (mm; PEMD) and fat depth (mm; PFAT), and post weaning weight (kg; PWWT). Across the 7.8 unit range of sire PEMD, carcass lean weight increased by 7.7%. This lean was distributed to the saddle section (mid-section) where lean became 3.8% heavier, with fore section lean becoming 3.5% lighter. Reducing sire PFAT across its 5.1 unit range increased carcass lean weight by 9.5%, and distributed lean to the saddle section which was 3.7% heavier. Increasing sire PWWT increased lean at some sites in some years, and on average increased saddle lean by 4% across the 24.7 unit PWWT range. Changes in lean weight and distribution due to selection for carcass breeding values will increase carcass value, particularly through increased weight of high value loin cuts.

Effects of palm oil and calcium soaps of palm oil fatty acids in fattening diets on digestibility, performance and chemical body composition of lambs

The effects on digestibility, performance and chemical body composition of inclusion of palm oil (PO, VETALGRAS ®) or calcium soaps of palm oil fatty acids (CaF, MAGNAPAC ®), at two levels, in diets of growing lambs were determined. Experimental diets consisted of barley straw and one of five concentrate supplements: control (C, no fat added), low level of PO (LPO, 25 g PO/kg), low level of CaF (LCaF, 31 g CaF/kg), high level of PO (HPO, 41 g PO/kg) and high level of CaF (HCaF, 50 g CaF/kg). Concentrations of supplemental fatty acids in the diets were 25 and 41 g/kg for the two supplementation levels. Concentrates with added fat were formulated to be isonitrogenous and isoenergetic and the five supplements had the same energy:protein ratio. The experiment was completed with 30 male Ojalada lambs (6 lambs per treatment) from weaning (initial live weight 14.1 ± 0.5 kg) until 25 kg live weight. Inclusion of fat decreased digestibility of acid detergent fibre (0.525 versus 0.438, P<0.05) and increased ether extract digestibility (0.645 versus 0.770, P<0.05). Ether extract (EE) digestibility increased (LPO and LCaF versus HPO and HCaF, P<0.05) when the level of added fat increased (0.727 versus 0.814). There was a significant effect of interaction (P<0.05) between the level and type of fat on the organic matter (OM) and neutral detergent fibre (NDF) digestibility of the diets. Diets HPO presented lower digestibility values (LPO versus HPO, P<0.05) than LPO with regard to OM (0.844 versus 0.819) and NDF (0.503 versus 0.435). Nevertheless, this effect was not observed when fat was added in the form of calcium soaps (LCaF versus HCaF, P>0.05). At the low level of fat inclusion, OM digestibility was greater when fat was in the form of PO than when it was as CaF (0.844 in LPO versus 0.823 in LCaF, P<0.05). At the high level of fat inclusion, NDF digestibility was greater when fat was included in the form of CaF rather than PO (0.435 in LPO versus 0.500 in HCaF, P<0.05). Average daily gain (ADG) and days to 25 kg were not affected by the treatments. The feed conversion ratio (FCR, g DMI/g daily gain) was lower (C versus LPO, LCaF, HPO and HCaF, P<0.05) when fat was added to the diets than control animals (3.21 versus 2.86). The treatments studied produced no differences in carcass yield. Statistically significant differences in chemical composition and energy content of carcass and non-carcass components were not observed. Inclusion of up to 41 g of fat from palm oil or calcium soaps of palm oil fatty acids per kilogram of the concentrate of growing lambs improves EE digestibility and the feed conversion ratio without affecting carcass yield and body chemical composition. Inclusion of palm oil fatty acids as calcium soaps avoided the negative effects on fibre digestibility observed when 41 g PO/kg were added to the diet.

Computer tomography and ultrasound measurement as methods for the prediction of the body composition of lambs

In Austria, performance testing in sheep breeding is carried out either with computer tomography or ultrasonography. The aim of this study was to compare the two methods on a sample of 41 male lambs (19 Merino, 14 Suffolk, and 8 Texel). To estimate the actual composition of the animals, one-half of their carcass was dissected into muscle, fat and bone after slaughter. Total fat in the carcass ranged from 8.8 to 28.5%, while the muscle was between 49.5 and 67.4%. The correlations obtained between the actual fat in the carcass and fat content measured with computer tomography or ultrasonography was 0.88 and 0.72, respectively. Corresponding correlations for muscle content were 0.68 and 0.48, respectively. Computer tomography is more accurate in predicting the actual body composition, on the other hand, ultrasonography is a cheaper equipment with lower operating costs. The predictions for fat content were more accurate than muscle content in the present study. One can conclude from the two invasive methods that both are useful tools for the prediction of body composition of lambs in animal breeding.

Composição corporal e exigências nutricionais de magnésio, potássio e sódio de cordeiros santa inês e seus cruzamentos com bergamácia, ile de france e texel dos 15 aos 45 kg de peso vivo

O presente trabalho foi conduzido no setor de Ovinocultura do Departamento de Zootecnia da Universidade Federal de Lavras-MG, com o objetivo de determinar a composição corporal e estimar as exigências nutricionais dos macroelementos minerais Magnésio (Mg), Sódio (Na) e Potássio (K), para ganho de cordeiros em crescimento. Foram utilizados 48 cordeiros machos inteiros, sendo 12 Santa Inês X Santa Inês (SI X SI), 12 Bergamácia X Santa Inês (BE X SI), 12 Ile de France X Santa Inês (IF X SI) e 12 Texel X Santa Inês (TE X SI). Três animais de cada grupo genético foram abatidos no início do experimento para determinação das quantidades de Mg, Na e K retidos em seus corpos, servindo como animais-referência para a técnica do abate comparativo. Os animais remanescentes de cada grupo genético foram confinados até atingirem os pesos pré-determinados para o abate de 25, 35 e 45 kg de peso vivo. A composição corporal em Mg, Na e K foi estimada por meio de equações de predição, obtidas pela regressão do logaritmo da quantidade dos minerais presentes no corpo vazio em função do logaritmo do peso do corpo vazio (PCV). As exigências líquidas de Mg, Na e K para o ganho em peso foram estimadas a partir da derivação das equações de predição da composição corporal. A composição corporal de Mg do grupo genético Santa Inês diferiu dos demais grupos, e para animais de 15 e 45 kg de peso vivo, o valor encontrado foi: 0,606 e 0,514 g de Mg/kg de PCV para os animais puros Santa Inês e 0,524 e 0,475 g de Mg/kg de PCV para os demais grupos genéticos. No caso do Na e K houve diferenças nas estimativas para o grupo genético IF X SI sendo os valores: 1,604 e 1,219 g de Na/kg de PCV e 1,938 e 1,592 g de K/kg de PCV, para os demais grupos genéticos, os valores foram: 1,665 e 1,270 g de Na/kg de PCV e 2,144 e 1,685 g de K/kg de PCV. As estimativas das exigências líquidas de Mg, encontrada nesta pesquisa, foram: 0,40 g e 0,35 g de Mg/kg de PV para animais puros Santa Inês e 0,38 g e 0,33 g de Mg/kg de PV para os demais animais com 15 e 45 kg de peso vivo, respectivamente. As exigências líquidas de K e Na estimadas nesta pesquisa para animais de 15 e 45 kg de peso vivo: 1,30 g e 1,06 g de K/kg de PV, 0,99 g e 0,75 g de Na/kg de PV para animais IF X SI e 1,37 g e 1,07 g de K/kg de PV e 1,03 g e 0,78 g de Na/kg de PV para os demais animais.

Body composition of lambs receiving 30 or 60 days of exercise training and (or) fenoterol treatment

The interaction between exercise and the β-adrenergic agonist, fenoterol, on body composition and muscle protein turnover was studied in this investigation. Forty young Hampshire × Rambouillet lambs were assigned to control (CON), exercised (EX), fenoterol-treated (5 ppm) (FEN), or fenoterol-treated and exercised (FENEX) groups. Lambs assigned to the exercise treatments were trained to run on a 10° inclined treadmill. The lambs were slaughtered after 30 or 60 days of treatment. Average daily gain tended ( p=0.09) to be greater, and feed:gain was significantly lower ( p=0.03) in the EX group than in the FENEX group by 30 days of treatment. By 60 days of treatment, kidney and pelvic fat and bodywall thickness were least in the EX group. Leg weights increased significantly with time only in the FEN and FENEX groups, whereas shoulder weights increased with time in all but the EX group. The latter effect was due to a cessation of adipose tissue growth in the EX lambs. There were significant time × treatment effects for the M. biceps femoris, M. gluteus medius, M. quadriceps femoris, M. semimembranosus, M. semitendinosus, M. infraspinatus, and M. pectoralis profundus. In every case, the time × treatment interaction was caused by nonsignificant growth of muscles in the CON group between 30 and 60 days. For the M. biceps femoris, M. quadriceps femoris, and M. gluteus medius, muscle mass increased with time only in the FENEX lambs. There was no increase in leg subcutaneous or intermuscular adipose tissue mass between 30 and 60 days in the EX lambs, although 50–70% increases in adipose tissue mass were observed over time in the other groups. Calpain and calpastatin activities in M. biceps femoris were not affected by treadmill exercise, fenoterol administration, or time × treatment ( p > 0.72 for all effects). Myosin light chain-1 gene expression in the FENEX lambs was depressed by 60 d, suggesting that the rate of M. biceps femoris growth in this treatment group was slowing by this time.

Animal performance and chemical body composition of lambs fed diets with different protein supplements

Thirty six Merino lambs with average initial live weight of 13.5 kg (SE±0.56 kg) were used in a 3×3 factorial arrangement (4 lambs per group). The treatments were three concentrate supplements (barley [B], barley 82.5% plus soybean meal 14.5% [BSM] and barley 82.5% plus meat meal 14.5% [BMM]) and three slaughter weights (20, 25 and 30 kg live weight). The lambs fed the B diet consumed less concentrate supplement (0.701 vs. 0.780b and 0.758b kg DM day −1, P<0.05) gained weight less rapidly (217 vs. 304b and 304b g day −1, P<0.01) and had a greater food conversion ratio (3.29 vs. 2.64b and 2.57b g DM supplement kg −1 LW gain, P<0.01) than the lambs on the BSM and BMM treatments respectively. Lambs supplemented with B were characterised by the highest fat and energy deposition ( P<0.01) in both components of the empty body weight (carcass and `non-carcass'). Although diet protein concentrations were different between supplements (B: 165.5, BSM: 219.3 and BMM: 237.2 g kg −1 DM), there were no differences ( P>0.05) in crude protein intake between BSM and BMM. (171.0 vs. 179.7 g crude protein day −1). The source of dietary protein (soybean meal vs. meat meal) did not have a significant influence ( P>0.05) on performance and chemical body composition of lambs. The interactions between the effect of slaughter weight and the concentrate supplement were non-significant ( P>0.05). This study suggests that meat meal can successfully replace soybean meal as a protein supplement for growing lambs from weaning to 30 kg live weight and offer an alternative to soybean meal as a regional protein source for lamb diets.

Effects of blood meal, fish meal, soybean meal or casein on growth and body composition in lambs

Thirty-two rams of Polish Merino breed, average initial body weight 25 kg (SE ± 0.8 kg) were fed isonitrogenous and isoenergetic diets in which the main sources of protein were blood meal (BM), fish meal (FM), soybean meal (SBM) or casein (C). The highest gains ( P < 0.05) were obtained in lambs fed FM diets (197 g day −1), followed by BM, SBM and C (181 g, 175 g and 114 g day −1, respectively). Lambs supplemented with C were characterised by the highest protein and energy consumption per kilogram body weight (BW) gain. Source of protein did not affect chemical composition of empty BW. The highest values of the k f coefficient were found in lambs fed FM (0.38) and the lowest in those fed C (0.20). Protein deposition was highest ( P < 0.05) in animals fed FM (35.5 g day −1), followed by BM, SBM and C (31.7 g, 30.0 g and 23.7 g day −1, respectively). FM was the optimal source of supplemental protein.

Prediction of the body composition of lambs from the composition of their non-carcass components

AbstractInformation on the chemical composition of Suffolk × Blackface lambs was collected and used to predict empty body (EB) component weights from empty body weight (EBW) and non-carcass (NC) component weights. EBW accounted proportionately for 0·94, 0·89 and 0·95 of the variation in EB crude protein, fat and energy content. A combination of NC component weights accounted proportionately for 0·94, 0·95 and 0·96 of the variation in EB crude protein, fat and energy content. EBW and a combination of NC component weights together accounted proportionately for 0·97, 0·97 and 0·98 of the variation in EB crude protein, fat and energy content. Chemical analysis of NC components is cheaper and easier than whole body analysis and provides a viable alternative to sample joint or specific gravity analysis.

Effects of indoor or outdoor rearing on the chemical composition of lambs

AbstractPure Merinos d'Aries male lambs were reared indoors (IN), with hay and concentrates, or outdoor (OUT) on improved Mediterranean range (Garrigues) and slaughtered when they reached 25 (light) or 32 (heavy) kg live weight. The alimentary tract weight was significantly affected by slaughter weight and by rearing method, which also significantly modified rumen contents. IN lamb body composition was higher in fat and energy and lower in water and protein than OUT lambs but differences induced by the rearing method were reduced when slaughter weight was increased. Allometric equations established for each environment were used to determine body composition and body gain composition at 20 and 25 kg empty body weight. Changes were very limited for IN lambs but protein and fat content of OUT lambs changed greatly as a result of the tremendous increase of grass availability towards the end of the fattening period.

Protein content in the diet for fattening lambs. 1. Liveweight gain, efficiency of feed utilization and digestibility of nitrogen and amino acids in the smali intestine

1. Effects of blood meal, fish meal, soybean meal or casein on growth and body composition in lambs M. Urbaniak Small Ruminant Research CrossRef

The effect of post-ruminal infusion of protein or energy on the pathophysiology of Trichostrongylus colubriformis infection and body composition in lambs

The effect of post-ruminal infusion of protein or energy on the pathophysiology of Trichostrongylus colubriformis infection and body composition in lambs was investigated using the comparative slaughter technique. Of 52 Dorset DownxCoopworth wether lambs (mean body weight 30.5, s.e. 0.44 kg), 8 comprised an initial slaughter group (IC), 36 were infected daily, per os, with 3000 Trichostrongylus colubriformis larvae per animal, and the remainder (C) were parasite-free controls. Groups of 12 infected animals were given either a continuous infusion (via abomasal catheter) of 50.4 g/day crude protein as sodium caseinate (PI), glucose (EI) in isocaloric amounts to PI, or a solution containing P and Na at the same rate as the caseinate infusions (SI). Uninfected controls (C) were also infused with this solution. Animals were slaughtered after 6 and 12 weeks for estimation of worm count and body composition. All animals were offered, ad libitum, meadow hay (118 g crude protein/kg dry matter (DM); 930 g organic matter/kg DM; 0.65 organic matter digestibility). DM intake of infected animals decreased by approximately 22% in PI and EI and by 32% in SI animals. Mean total metabolizable energy (ME) intake during the experiment (inclusive of infusions) was C, 0.607; PI, 0.687; EI, 0.704; SI, 0.617, s.e.d. 0.0308 MJME (kg W)-0.75 day-1. Nitrogen retention in infected sheep was increased fourfold by protein infusion and twofold by energy infusion. The rate of energy retention was reduced by infection, increased by protein infusion but only partly by energy infusion. Protein infusion reduced mean faecal egg output and mean total parasite count. Increased endogenous plasma loss into the gastrointestinal tract was similar in all infected groups. It was concluded that a major limiting factor in efficient food utilization in animals with gastrointestinal nematode infections is a parasite-induced protein rather than energy deficiency, possibly the result of increased endogenous protein losses into the gastrointestinal tract. The debilitating effect of internal parasites could be markedly reduced by increasing duodenal protein supply.

Procedural and mathematical considerations in urea dilution estimation of body composition in lambs.

Two experiments (n = 46 and 56, respectively) were conducted to evaluate urea dilution as an estimator of body composition in lambs and to address certain procedural and mathematical considerations in this technique. In Exp. 1, 14 blood samples were taken over 240 min after urea infusion. The equation describing the urea clearance curve was: delta PUN = 9.7e-.1727(min) + 10.4e-.0021(min), pools 1 and 2, respectively (r2 = .99, P less than .001; individual lamb effects removed). In the combined experiments, urea space (US) was related to percentage of empty body water (PEBH2O) by the equation 31.7 + .471 US (empty body weight basis; r2 = .56, P less than .001). The regression equation indicates that the US-PEBH2O relationship in lambs is different from that reported in cattle, even though urea clearance kinetics are similar. Although the prediction equations appeared to be biologically valid, considerable error was associated with the composition estimates. The PEBH2O was predicted as well by live weight (r2 = .69; SEy.x = 3.0) as by US in these experiments. The two-sample method (T12 minus T0) to determine the change in marker concentration was shown to be related more closely (r2 = .56) to PEBH2O than the standard multisample extrapolation to T0 method (r2 = .0 and .38 for pools 1 and 2, respectively). An equilibration time of 9 to 12 min provided the best estimate of body composition in lambs.(ABSTRACT TRUNCATED AT 250 WORDS)