Composition Of Sheep Research Articles

Época de nascimento sobre a composição regional e tecidual da carcaça de cordeiros da raça Texel

Foram avaliados os efeitos de épocas alternativas de nascimento sobre a composição regional e tecidual da carcaça em ovinos. Quarenta e nove cordeiros machos não-castrados da raça Texel, nascidos em duas épocas (agosto e novembro), foram mantidos em regime de pastagem e abatidos com média de idade de 129 e 164 dias, respectivamente. Previamente aos abates foi feita a avaliação da produção forrageira do campo pelo método Botanal. Foram verificadas melhores condições forrageiras para os cordeiros nascidos em agosto, que apresentaram maior peso e proporção na maioria dos cortes, assim como menor proporção de músculo na paleta e perna; apresentando maior conteúdo de tecido adiposo na maioria dos cortes da carcaça. Para os cordeiros nascidos em novembro, ocorreu maior relação músculo:gordura e músculo:osso na paleta e na perna, assim como maior relação músculo:gordura no costilhar. As condições nutricionais são responsáveis pelas diferenças nos pesos e rendimentos dos cortes, assim como na composição tecidual da carcaça, em cordeiros mantidos em regime de pasto, viabilizando o uso de época alternativa de nascimentos para incrementar a oferta de animais para o abate.

Validation of the n-alkane and NIRS techniques to estimate intake, digestibility and diet composition in sheep fed mixed lucerne: ryegrass diets

An experiment was carried out with sixteen non-pregnant, non-lactating adult Rasa Aragonesa ewes fed different proportions of lucerne and ryegrass hays to validate the use of n-alkanes and NIRS methods to estimate diet composition, intake and digestibility. The effect of two different faecal sampling procedures (daily pool (S1) or rectal spot samples (S2)) was also tested. The faecal concentration of n-alkanes was affected by the sampling procedure, although differences were lower than 12%. Faecal recoveries were not affected by diet, except in the case of C 23 ( P < 0.0001), C 28 ( P = 0.0264) and C 33 ( P = 0.0241), and followed a curvilinear pattern with alkane chain length. Recovery was complete in the case of C 29, C 31 and C 33, which countersigns the usefulness of these internal markers for digestibility and digestive flow studies (especially C 31, given its high concentration in most plants). The faecal recoveries of C 31 and C 32 were not similar, the assumption of identity affecting in an important way the reliability of intake estimates. The NIRS methodology appeared as a promising alternative for predicting diet composition ( R 2 of the cross-validation = 0.98) and faecal concentration of most natural alkanes, although that was not the case for dosed alkanes. In all cases, the prediction equations obtained from the spectra of the faecal spot samples were better than those obtained from daily pool samples.

Faecal alkane recoveries from multi-component diets and effects on estimates of diet composition in sheep

In a feeding trial with sheep, four animals each were fed one of the three roughages (perennial ryegrass (PR), meadow fescue (MF) and red clover (RC)) or one of the four different mixtures (g/day 250 : 250 : 250, 375 : 75 : 300, 525 : 187.5 : 37.5 and 75 : 525 : 150, respectively) of those three roughages, both with and without the inclusion of 100 g of beeswax-labelled barley. Further, four sheep received a pure lucerne diet to enlarge available data on single species faecal recoveries. All sheep except those fed single-component diets and the 250 : 250 : 250 roughage mix were administered intra-ruminal alkane controlled-release devices (CRD). The aim of the study was to investigate the effect of diet composition on faecal alkane recoveries, and to assess the accuracy of the alkane-based estimate of diet composition and intake based either upon a general set of faecal recoveries across diets or upon dietary recoveries and dietary samples more specifically attributable to individual dietary treatments. For each roughage component independently, the accuracy of diet composition estimates was assessed using linear regression across all diets. The estimates of the proportion of barley were analysed further using mean differences and mean prediction errors. Faecal alkane recovery increased with increasing chain length and was affected by diet composition. RC had a significantly higher faecal recovery for alkanes C25, C27, C29 and C31 than at least one of the other single-roughage diets. When considering mixed diets consisting of PR, MF, RC and barley, the composition of the roughage component significantly affected faecal recovery of all alkanes except C30 and C33. The inclusion of beeswax-labelled barley caused a decrease in faecal recovery of alkanes up to C29. This effect was attributable to the beeswax rather than the barley itself. By contrast, the decrease of faecal recovery of synthetic dosed alkanes from the CRD in diets containing barley, compared with the corresponding diets without barley, was attributable to the supplement itself. It was concluded that synthetic dosed alkanes behaved differently during gut transit from natural alkanes. The proportions of individual dietary components were estimated well over a wide range of proportions. Generally, the more information available, the more accurate the estimates achieved. However, a general set of faecal alkane recoveries and bulked samples of dietary components yielded estimates of diet composition sufficiently accurate for a large number of studies, especially in situations where groups of animals are of concern and not the individual animal.

P1-13 Effects of dam body mass, feeding during pregnancy and birth rank on body composition in sheep

P1-13 Effects of dam body mass, feeding during pregnancy and birth rank on body composition in sheep

Accuracy of dual energy X-ray absorptiometry, weight, longissimus lumborum muscle depth and GR fat depth to predict half carcass composition in sheep

A Hologic QDR4500W dual energy X-ray absorptiometer (DXA) was used to measure body composition in 60 sheep half carcasses ranging from 8 to 28 kg. Half carcasses were from ewes and wethers of mixed genetics. Values determined by DXA, including total tissue mass (TTM), lean tissue mass (LTM), fat tissue mass (FTM) and bone mineral content (BMC), for the half carcass were evaluated by comparison with chemically determined composition. In the case of BMC, the relationship was with chemically determined ash content. Liveweight and chemically determined lean, fat and ash were strongly related to DXA-derived values for TTM, LTM, FTM and BMC, respectively (R2 = 0.999, 0.986, 0.989 and 0.920, respectively). However, because DXA estimates were different from chemically determined values in this sample of carcasses, they needed to be adjusted with the use of appropriate regression equations to correct the in-built algorithms. These data demonstrate the efficacy of DXA as a non-destructive method for determining the composition of the sheep half carcass.

Genetic analyses and quantitative trait loci detection, using a partial genome scan, for intramuscular fatty acid composition in Scottish Blackface sheep1

Genetic parameters for LM fatty acid composition were estimated in Scottish Blackface sheep, previously divergently selected for carcass lean content (LEAN and FAT lines). Furthermore, QTL were identified for the same fatty acids. Fatty acid phenotypic measurements were made on 350 male lambs, at approximately 8 mo of age, and 300 of these lambs were genotyped across candidate regions on chromosomes 1, 2, 3, 5, 14, 18, 20, and 21. Fatty acid composition measurements included in total 17 fatty acids of 3 categories: saturated, monounsaturated, and polyunsaturated. Total i.m. fat content was estimated as the sum of the fatty acids. The FAT line had a greater i.m. fat content and more oleic acid, but less linoleic acid (18:2 n-6) and docosapentaenoic acid (22:5 n-3) than did the LEAN line. Saturated fatty acids were moderately heritable, ranging from 0.19 to 0.29, and total SFA were highly heritable (0.90). Monounsaturated fatty acids were moderately to highly heritable, with cis-vaccenic acid (18:1 n-7) being the most heritable (0.67), and total MUFA were highly heritable (0.73). Polyunsaturated fatty acids were also moderately to highly heritable; arachidonic acid (20:4 n-6) and CLA were the most heritable, with values of 0.60 and 0.48, respectively. The total PUFA were moderately heritable (0.40). The QTL analyses were performed using regression interval mapping techniques. In total, 21 chromosome-wide QTL were detected in 6 out of 8 chromosomal regions. The chromosome-wide, significant QTL affected 3 SFA, 5 MUFA, and 13 PUFA. The most significant result was a QTL affecting linolenic acid (18:3 n-3) on chromosome 2. This QTL segregated in 2 of the 9 families and explained 37.6% of the phenotypic variance. Also, 10 significant QTL were identified on chromosome 21, where 8 out of 10 QTL were segregating in the same families and detected at the same position. The results of this study demonstrate that altering carcass fatness will simultaneously change i.m. fat content and oleic, linoleic, and docosapentaenoic acid content. The heritabilities of the fatty acids indicate opportunities for genetically altering most fatty acids. Moreover, this is the first report of detection of QTL directly affecting fatty acid composition in sheep.

The use of alkanes as markers for estimating diet composition in sheep and goats

SummaryAn experiment was carried out to evaluate the use of alkanes for estimating diet composition of goats and sheep offered three different dietary treatments. Twelve animals as two groups of 4 crossbred goats (G1, 24 kg live weight; G2, 22 kg) and 4 crossbred sheep (S, 26 kg live weight), were housed in metabolism pens. Animals were offered daily a total of 1 kg DM/100 kg live weight. G1 received 70% ryegrass (Lolium perenne) and 30% gorse (Ulex gallii), G2 received 70% ryegrass and 30% heather (Erica sp.) and S group ate 100% ryegrass. Diet composition was estimated from the alkane concentrations (using all alkanes from C23 to C36 or only odd-chain alkanes C27, C29, C31 and C33) in diet and faeces (with or without correction for incomplete faecal recoveries) using least-squares procedures.Dietary treatment and animal species significantly affected alkane faecal recoveries, except for C24 and C36. When applying the faecal recovery corrections, there were no significant differences between measured proportions of dietary components and those estimated using all alkanes or odd-chain alkanes. In contrast, the proportions calculated without faecal recovery correction differed significantly (P&lt;0.05) from the actual proportions and over-estimated the amount in the diet of those plant components with higher concentrations of long-chain alkanes (Erica sp. and Lolium perenne). The results indicate that alkanes are useful markers to estimate diet composition, however, it was observed that animal species and diet composition influenced the faecal recovery of alkanes. This suggests that the use of the alkane methodology for estimating the diet selection of grazing animals should be preceded by a calculation of the actual alkane faecal recoveries for each experimental condition.

Milk and Cheese Fatty Acid Composition in Sheep Fed Mediterranean Forages with Reference to Conjugated Linoleic Acid cis-9,trans-11

Two experiments were undertaken to evaluate the effect on milk and cheese fatty acid composition of feeding different fresh forages to dairy sheep both in winter (experiment 1, growing stage of the forages, early lactating ewes) and in spring (experiment 2, reproduction stage of the forages, midlactating ewes). Four forage species were compared: annual ryegrass (RY, Lolium rigidum Gaudin), sulla (SU, Hedysarum coronarium L.), burr medic (BM, Medicago polymorpha L.), and a daisy forb (CH, Chrysanthemum coronarium L.). The forages were cut twice daily and offered ad libitum to 4 replicate groups of Sarda dairy sheep (groups RY, SU, BM, and CH). The CH forage was particularly rich in linoleic acid in both periods, whereas BM and SU forages were rich in linolenic acid in winter and spring, respectively. Milk fatty acid composition was affected by the forage in both experiments. Milk conjugated linoleic acid and vaccenic acid contents were higher in CH and BM groups (winter) and CH group (spring) than in the other groups. No differences were observed when comparing fatty acid profile between milk, 1-d-old cheeses, and 60-d-old cheeses within experimental groups, suggesting that the fatty acid recovery rates during cheese making and ripening were not affected by the feeding regimens. After stepwise discriminant analyses of the pooled data, the milks and cheeses sourced in the different feeding regimens differed among them. Based on these results, we conclude that it is possible to manipulate the fatty acid profile of sheep dairy produce to maximize the content of beneficial fatty acids by the use of appropriate fresh forage-based regimens.

Pre-delivery Changes in Amniotic Fluid Volume and Composition in Sheep

To determine the changes in amniotic fluid (AF) volume and solute concentrations during the last 3 weeks of gestation in fetal sheep with a ligated urachus. AF volume as well as solute concentrations of AF, fetal urine, fetal blood, and maternal blood were measured serially over the last 24 days of gestation in chronically catheterized fetal sheep. Statistical analyses included regression analysis and analysis of variance (ANOVA). Delivery occurred at 145.5 +/- 1.1 (SE) days (n = 11 animals). AF volume averaged 913 +/- 46 mL (n = 119 determinations total from 11 animals) and was unchanged with time when analyzed against either gestational age (P = .9) or time prior to delivery (P = .81). Amniotic osmolality, sodium, chloride, glucose, and calcium concentrations decreased as gestation progressed, while potassium and lactate concentrations increased. Only amniotic lactate underwent a pre-delivery increase in concentration. From multivariate regression, AF solute concentrations correlated positively with fetal blood and urine concentrations and negatively with gestational age. In fetal sheep with a ligated urachus, AF volume does not decrease prior to labor and delivery. This differs from the sharp pre-delivery decrease in AF volume that occurs in rats, mice, and pigs and is similar to the relatively constant AF volume in humans, baboons, and monkeys. Further, pre-delivery changes in AF lactate concentration may reflect the consequences of a low AF volume. Regression analysis suggests that fetal blood and urine independently contribute to AF solute concentrations and that gestational age-specific changes in intramembranous transport also may contribute.

Two methods of using X-ray Computed Tomography to predict carcass composition in sheep

X-ray computed tomography (CT) can be used to accurately assess carcass composition in sheep (Sehested, 1984; Young et al., 2001) both in research and commercially, as part of a breed selection programme. Two different CT scanning methods have been used: a) the reference scan method where tissue weights are predicted from tissue areas in a small set of cross-sectional scans at ‘anatomical landmarks’, and b) the Cavalieri method where a larger number of scans are taken along the body. It is of interest to examine the accuracy of evaluations made using these two methods and the individual merits of the two methods depending on their application.

The use of NIRS for prediction of intake, digestibility and diet composition in sheep fed mixed grain:roughage diets

The use of NIRS for prediction of intake, digestibility and diet composition in sheep fed mixed grain:roughage diets

Seasonal botanical and chemical composition of sheep and goat diets on a common range in eastern Africa

The botanical and chemical composition, intake and digestibility of local sheep (Ovis aries) and goat (Capra hirtus) diets were evaluated over the wet (growing) and dry (dormant) seasons. Diet botanical composition was related to the vegetation composition on the range. Commiphora riperia and Acacia tortilis were the most dominant tree species, while Duosperma kilimandscharicum and Premna hildebrandtii were the most dominant shrub species. Enteropogon macrostachyus, Cenchrus ciliaris and Chloris roxburghiana were the most abundant grass species, while Brepharis integriifolia, Commelina benghalensis and Macrotylomma axillare were the most dominant forb species. Grasses increased towards the end of the wet season and the beginning of the dry season, while the forbs decreased. Eragrostis caespitosa, Cenchrus ciliaris, Eragrostis superba, Enteropogon macrostachyus and Themeda triandra were the most dominant grass species in sheep diets during both seasons, accounting for over 82% of the diet. Acalypha fruticosa, Grewia similis and G. bicolor were the most important browse species in goat diets in both seasons, while Eragrostis caespitosa and E. superba were the most common grass species during both seasons. Overall, goat diets comprised 81% browse, 17% grass and 2% forbs during the wet season; and 82% browse, 15% grass and 3% forbs during the dry season. Whilst the goat diets had higher (P < 0.05) Crude Protein (CP) content than sheep diets during both seasons, the sheep diets were lower in lignin content than goat diets during the wet season. Overall, the goat diets were lower in Neutral Detergent Fibre (NDF) and Acid Detergent Fibre (ADF) than sheep diets during both seasons. There was no difference (P < 0.05) in digestibility between the two animal species. However, it was higher (P < 0.05) during the dry than the wet season. Although sheep and goats are commonly herded together in east African rangelands, they have differing abilities to utilise forages. These differences must be taken into consideration in grazing management decisions, and selected grazing areas should be able to cater for the forage requirements of both species.

Validation of the n-alkane technique to estimate intake, digestibility, and diet composition in sheep consuming mixed grain:roughage diets

The usefulness of the n-alkane technique to estimate intake, digestibility, and diet composition in sheep fed mixed diets was tested in an experiment with 16 ewes consuming 4 different proportions of barley grain and straw ranging from 15:85 to 60:40. Two cases were considered: (1) straw as one component or (2) straw separated into leaves and stems. The relationship between estimated (Y) and observed (X) proportion of grain in the diet was highly significant (1: Y = 0.2355 + 0.9945X, r2 = 0.9999; 2: Y = –2.472 + 1.0063X, r2 = 0.9999). Actual intake was overestimated in (1) by 3.43–12.40%, the largest discrepancies corresponding to the lowest proportions of grain. In (2) actual intake was either overestimated (2.69%) or underestimated (5.38–6.85%), without a clear effect of the diet. A similar pattern was observed for digestibility, which was overestimated in (1) by 1.65–9.59% and overestimated, (by 2.07%) or underestimated (by 3.80–4.62%) in (2). Due to the small discrepancies between observed and estimated values, it may be concluded that the n-alkane technique might be a valid method for estimating intake, digestibility, and diet composition in sheep consuming mixed diets, for the two latter provided that faecal recovery of individual n-alkanes is calculated with enough accuracy.

The effects of different amounts and types of fat on milk fatty acid composition in sheep

The effects of different amounts and types of fat on milk fatty acid composition in sheep

The effects of different amounts and types of fat on meat fatty acid composition in sheep

The effects of different amounts and types of fat on meat fatty acid composition in sheep

Genotype-related variations in subcutaneous fat composition in sheep

AbstractThe aim of this research was to study the effect of genotype on the fatty acid composition in adult ewes and 5-to 6-month-old lambs of two mutton breeds (Suffolk and Pannon Sheep) and Booroola Merino. Samples of subcutaneous fat were obtained by surgical biopsy around the tailhead. Fatty acid composition of the adipose fat was determined by gas chromatography. Significant differences (P&lt; 0·05) were found in the fatty acid composition of the adipose tissue among the three breeds. Suffolk showed a lower (P&lt; 0·05) proportion of C12: 0 and C14: 0 fatty acids than the other two breeds. Considering the total quantity of saturated (TSFA) and the total quantity of unsaturated (TUFA) fatty acids, Booroola Merino showed a significantly (P&lt; 0·05) higher proportion of TSFA and lower proportion of TUFA in their adipose tissue than the mutton genotypes (Suffolk and Pannon Sheep). Higher proportions of C18: 0, C18: 3 and C20: 1 (P&lt; 0·05) but lower proportions of C12: 0, C14: 0, C16: 0, C16: 1 and C18: 2 (P&lt; 0·05) were found in the subcutaneous fat of adult ewes than in that of their female progeny. Sex differences were also observed in the study. The proportions of saturated fatty acids were higher (P&lt; 0·05) in female lambs than in males of the same age. These results indicate that a genetic approach may be useful to improve fatty acid composition of carcass lipids in sheep. However, age and sex differences also have to be taken into consideration.

Use of sire referencing schemes to select for improved carcass composition in sheep

Use of sire referencing schemes to select for improved carcass composition in sheep

Growth and carcass composition in sheep offered isoenergetic rations which resulted in different concentrations of ruminal metabolites

The objective of this study was to determine if isoenergetic rations, designed to result in different ruminal fermentation patterns, altered growth and carcass composition in wethers. Two basal rations, based either on starch (S) or a digestible fibre/sugar mixture (F) were formulated. Sodium propionate was included at 0 (C) or 40 g/kg (P) to give four isoenergetic (12 MJ metabolisable energy/kg dry matter) and isonitrogenous (165 g crude protein/kg dry matter) rations. When fed at 22 g/kg bodyweight (BW)+75 g hay daily to four ruminally fistulated sheep in a 4 (ration) by 4 (period) Latin square experiment, there was no difference between diets in mean volatile fatty acid concentrations in ruminal fluid (92, 90, 86 and 105 (S.E. 7.5) mmol/l for SC, SP, FC and FP, respectively). The acetate to propionate ratio was lower ( P<0.001) for S-based diets and decreased ( P<0.01) by the inclusion of P (1.28, 0.93, 1.98 and 1.70 (S.E. 0.035), for SC, SP, FC and FP, respectively). When fed to wethers (BW of 46.2 kg; n=6/treatment) for 64 days before slaughter, the digestible organic matter concentration (g/kg dry matter) measured in vivo was lower ( P<0.01) for S-based diets but unaffected by the inclusion of P (803, 812, 831 and 841 (S.E. 7.0) for SC, SP, FC and FP, respectively). Bodyweight gain and carcass weight were similar for all treatments (123, 123, 136 and 120 (S.E. 26.0) g/day and 26.2, 26.9, 27.7 and 26.6 (S.E. 0.87) kg for SC, SP, FC and FP, respectively). Inclusion of P decreased ( P<0.05) the proportion of dissectible fat in the carcass (267, 233, 250 and 223 (S.E. 10.3) g/kg for SC, SP, FC and FP, respectively). Inclusion of P increased ( P<0.05) estimated skeletal muscle growth when included in the S-based diet only (38, 64, 63 and 62 (S.E. 8.0) g/day for SC, SP, FC and FP, respectively). It is concluded that a decrease in the acetate to propionate ratio in ruminal fluid, by addition of sodium propionate, resulted in a decrease in fat deposition in both S- and F-based rations and increased skeletal muscle growth in the S-based ration.

Changes in body composition of sheep selected for high and low backfat thickness, during periods of ad libitum and maintenance feeding

AbstractCoopworth sheep from the high and low backfat selection lines and from one random-bred line developed at Invermay, New Zealand, were used to examine the interaction between the degree offatness of sheep and a period of maintenance feeding (from 20 to 35 weeks of age), in terms of total fat, carcass lean tissue, bone and viscera weights, relative to the empty body weight measured in computer-aided tomography scans. A similar study was done for weights of subcutaneous, intermuscular and internal (abdominal) fat partitions relative to total fat weight. During two a d libitum feeding periods (front 10 to 20 and from 35 to 43 weeks of age) changes in the same components relative to the ‘whole’ (empty body weight or total fat, depending on the case) were expressed in allometric terms.Only the allometric growth coefficient for total fat weight was significantly affected by the period of restricted feeding, decreasing after this period. No line or sex effect was observed on any growth coefficient. As a result, there were no changes in differences between treatments over the ad libitum feeding periods, with fat animals and females having significantly higher proportions of fat, while females also had a significantly lower proportion of intermuscular fat.During maintenance feeding, line and sex differences in dissectible component weights did not change significantly, except in terms of intermuscular fat, with the males showing an increasingly larger proportion than the females.

Responses of young energy-restricted sheep to chronically administered insulin-like growth factor I (IGF-I): evidence that IGF-I suppresses the hepatic growth hormone receptor.

We have shown previously that chronic administration (8 weeks) of insulin-like growth factor-I (IGF-I) has little growth-promoting effect in well fed sheep. The aim of this study was to investigate the anabolic effects of IGF-I in energy-restricted conditions in which circulating concentrations of IGF-I in control animals were expected to be low. Young castrate male sheep were offered chaffed lucerne at a rate equivalent to 110% maintenance and were treated by sc injection three times per day for either 8 or 12 weeks with recombinant human IGF-I (150 micrograms/kg live wt x day) or saline in a 2 x 2 factorial design (eight animals per cell). IGF-I treatment significantly increased plasma IGF-I concentrations, but reduced plasma concentrations of IGF-II, GH, urea, and creatinine. Treatment with IGF-I also decreased (P < 0.1) GH secretion in response to a GRF load, but significantly (P < 0.05) increased the nonesterified fatty acid response to an epinephrine load. The reduction in circulating GH levels was accompanied by a suppression of [125I]oGH binding to hepatic microsomal membranes. This effect, if apparent in other tissues, may act as a feedback mechanism to limit the local synthesis of IGF-I and could explain why IGF-I treatment had little effect on the growth rate of the sheep, although it did increase nitrogen digestibility of the feed consumed and decreased the fat content of the hind leg. It also differentially promoted the growth of the spleen, thymus, and mandibular salivary gland and increased blood counts of eosinophils. It is concluded that IGF-I does not have marked effects on growth rate or body composition in sheep fed a near-maintenance diet. Possible reasons include the associated suppression of GH secretion and action, which limits the ability of treated animals to repartition absorbed nutrients.