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The relationship between body development and external measures in sheep could provide useful information to define the optimal slaughter time as well as the adequate nutritional management. Thus, the objective of this study was to evaluate the morpho-functional diversity of Dorper sheep crossed with Brazilian native breeds using in vivo morphometric analysis. The animals evaluated were from crosses of Dorper with Morada Nova, Rabo Largo and Santa Ines sheeps. The animals were slaughtered at 120 and 240 days of age. Body and carcass measures, weight of meat cuts and growth were evaluated. The crossbred animals were analyzed by sex, totaling six treatments. A factorial analysis was performed using two sets of data: the in vivo morphometric measures, and all the other characteristics and these factors were used as new variables. The differences among treatments were analyzed using MANOVA and canonical analysis. The meat cuts, conformation, marketability adaptation, and early maturity of the animals slaughtered at 120 days, as well as the meat cuts, conformation, adaptation, early maturity, and hindquarter of the animals slaughtered at 240 days were evaluated. As regards body measurements, at both slaughter ages, the following factors were discriminated: height, robustness, length, and thoracic circumference. Animal slaughtered at 120 days of age showed greater differences whereas at 240 days the differences diminished allowing to individuate which treatments were more adaptive or productive. Crosses ½ Dorper × ½ Santa Ines (male and female), and ½ Dorper × ½ Rabo Largo male slaughtered at 240 days seem to show higher productivity and better marketability abilities. The other crosses tend to have a more rustic profile (less productive) and smaller size, reaching however adult size earlier and showing better adaptive characteristics, which allows to decide for slaughtering at younger ages.

The work consisted of the evaluation of photosensitization in sheep grazing signal grass (Brachiaria decumbens) in a silvopastoral system or under full sunlight for 60 days in the summer. We hypothesized that shade provided by trees in the silvopastoral system prevents or alleviates the classic symptoms of photosensitization in grazing sheep and affects the concentration of the saponin protodioscin in signal grass. Twenty naive crossbred sheep (Dorper x Santa Ines) were used in a randomized block design, with two blocks and five animals per block. Animals in both silvopastoral and full sun treatments grazed B. decumbens, and animals in both treatments presented with clinical symptoms, alterations in the liver, and increased serum levels of gamma-glutamyltransferase (GGT), aspartate aminotransferase (AST), and bilirubin over the duration of the experiment. Although the protodioscin content of B. decumbens in the silvopastoral system was lower than in the full sun treatment, it was sufficient to cause secondary photosensitization in the animals. The natural shading provided by the silvopastoral system does not prevent or ameliorate photosensitization symptoms in young naive sheep grazing on B. decumbens.

This study set out to define the energy and protein requirements for maintenance and lactation of Dorper☓Hu crossbred lactating ewes. Eighteen ewes of similar weight (53.37 ± 1.18 kg) were randomly divided into three groups after parturition: ad libitum (AL), IR70 % (intake restricted to 70 % of AL), and IR50 % groups (intake restricted to 50 % of AL). Energy, nitrogen, and carbon balance were calculated by determining the carbon or nitrogen content of orts, feces, urine, milk, CH4, and CO2 samples in digestibility and respiratory trials. Maintenance requirements of net energy [NEm; 257.04 ± 1.15, 252.35 ± 1.08, 244.34 ± 1.15 kJ/kg body weight (BW)0.75/day]; metabolizable energy (MEm; 353.29 ± 3.27, 352.16 ± 3.54, 354.97 ± 2.67 kJ/kg BW0.75/day); net nitrogen (NNm; 326 ± 110, 306 ± 81, 285 ± 77 mg/kg BW0.75/day); and net protein (NPm; 2.03 ± 0.17, 1.91 ± 0.28, 1.78 ± 0.28 g/kg BW0.75/day) were observed on 20th, 50th and 80th day of lactation. Compared with these results, the Wood’s model showed adequate estimates of peak yield (0.88 vs. 0.87 kg/day), but an overestimation of milk yield either side of the peak, and an underestimation of the timing of peak yield compared with the observed milk curve in the current study (4th vs. 3rd week of lactation, respectively). The corresponding NE requirements for lactation (NEL; MJ/kg milk) linearly increased with progressing lactation and were scaled from 3.76 to 4.19 (MJ/kg milk). Additionally, milk yield varied from 1–3 kg daily, and, from 20th to 80th day of lactation, the daily metabolizable protein (MP) requirement for lactation ranged from 141.14–283.43 g/day. The combined results suggest that the estimated MP and ME requirements for lactating Dorper and Hu crossbred sheep fell between the NRC recommendations for lactating ewes suckling a singleton and twin lambs.

There is an increasing economic pressure in sheep production. Hence, it is imperative to use all available tools contributing to improvements in lamb survival. In this regard, there is a lack of studies addressing the impact of maternal body condition traits on lamb performances during lactation. Specifically, the focus of the present study was to analyse associations between ewe traits reflecting maternal energy metabolism and lamb body weight (LBW), separately in a low and in a high input production system. The dataset considered 199 Merinoland- (ML) and 45 Rhonsheep (RH) ewes from the high input production system (> 33% concentrates in the ration), as well as 47 Coburger Fuchssheep (CF), 78 RH and eight crossbred (CB) ewes from the low input production system ( 100 kg EBW were 1.41 kg heavier at weaning than lambs from ML ewes 3 mm had significantly greater 12 W W (2.63 kg, P

This study aimed to investigate the relationship between microbial N (MN) yield and urinary excretion of purine derivatives (PD) from the rumen in Dorper × thin-tailed Han crossbred sheep. Twelve Dorper × thin-tailed Han crossbred, non-castrated male lambs (41.3 ± 2.8 kg body weight) fitted with ruminal and duodenal cannulae were randomly assigned to one of three levels of DM intake: ad libitum intake, 70%, or 50% of the ad libitum intake, with four lambs at each level. The MN yield from the rumen was measured using 15N or purine bases (PB) as a microbial marker, and urinary PD were determined by colorimetric methods. Microbial components (OM, N, PB and ratio of PB to N) were not affected (P > 0.05) by dietary treatment. The MN yield measured using PB was slightly lesser and more variable than using 15N. No difference in MN yield was found between markers. The efficiency of MN synthesis (g N/kg organic matter apparently digested in the rumen) was not affected (P > 0.05) by feed intake regardless of the marker used. Urinary PD decreased significantly (P < 0.05) with decreasing level of feed intake and the molar recovery of duodenal PB measured with digesta markers as urinary PD was 0.83 (r2 = 0.89, P < 0.001). Urinary PD excretion was linearly correlated with DOMI (r2 = 0.94, P < 0.001), and MN yield estimated by using either 15N or PB (r2 = 0.91 and 0.80, respectively, P < 0.001). These results suggest that urinary PD excretion is an accurate indicator of MN synthesized in the rumen, and an equation, MN (g/d) = 0.030 + 0.741 × PD (mmol/d), is proposed to predict the MN yield from the rumen of Chinese sheep.

The goal of the present work was to analyze the Brody, Von Bertalanffy, Richards, Logistic and Gompertz functions in order to describe the growth in crossbred sheep Dorper × Morada Nova (DMN), Dorper × Rabo Largo (DRL) and Dorper × Santa Ines (DSI). After defining the best adjusted model, the absolute growth rate was calculated and the influence of both environmental and genetic features on curve parameters was evaluated. The data were based on 156 F1 animals (36 DMN, 61 DRL and 59 DSI), weighed quarterly from birth up to 210 days of age. Both Gompertz and Logistic functions presented the best adjustment, being the latter slightly superior. The mature weight was statistically similar among the three genetic groups. However, the DSI group presented a faster growth during the pre-weaning period, with a remarkable fall from the inflection point on. The weight gain within such group was lower to those from DRL and DMN groups from 150 days of age on. Only the birth month has significantly influenced the asymptotic weight (A). The growth rate (k) was affected by birth month, type of parturition, sex, genetic group and parturition type vs. genetic group interaction. The estimated correlation between the parameters A and k were negative (−0.58 for DMN, −0.39 for DSI and −0.38 for DRL), indicating that more precocious animals are less likely to reach higher weights when adults.

A commercial crossbreeding experiment at the Research Farm of Cukurova University in Adana with Ile-de-France, Rambouillet, Chios and Awassi sheep is reported. The Chios breed was chosen for prolificacy and high milk production potential, the Ile-de-France for early growth and carcass quality, and the Rambouillet for early growth; the Awassi is the local sheep which is to be improved. The objective was to increase meat production by exploiting the reproductive efficiency of crossbred sheep. Firstly, Awassi ewes were mated with Chios rams, producing the F1 generation. Secondly, the F1 ewes were mated with Ile-de-France sires to obtain F1 ram lambs (designated IlF1), and F1 ewes were also mated with Rambouillet sires to obtain F1 ram lambs (designated RF1). Rambouillet (Rmb) and Awassi (Aw) sheep served as the control lines. Lambing rate (lambs born per mated ewe) was 1.65, 1.16, 1.05 and 1.03 for Il × F1, R × F1, Aw × Aw and Rmb × Rmb matings respectively. Twelve ram lambs in the IlF1, RF1 and Aw groups, and eight Rmb ram lambs were used in a fattening trial. Ram lambs weighing 38–40 kg were slaughtered and the chilled carcass was divided into eight primal cuts. Average daily gains were 311.6, 253.2, 281.2 and 226.0 g for IlF1, Aw and Rmb lambs, respectively, and feed efficiency was 3.8, 4.2, 3.7 and 5.4. Dressing percentage was higher for IlF1 lambs than for other groups. For cold carcasses of IlF1, RF1 Rmb and Aw lambs, the total bone percentage was 18.8, 19.5, 19.5 and 19.7 respectively, total muscle percentage 54.9, 53.5, 54.3 and 54.1, total subcutaneous fat percentage 12.3, 14.1, 11.6 and 16.6, and total intermuscular fat percentage 10.5, 9.5, 10.1 and 6.6. Fat thickness and rib-eye areas at the 12th rib were generally largest for IlF1 ram lambs.