Performance, carcass characteristics and non-carcass components of Santa Ines and crossbred (Santa Ines x Dorper) lambs finished in different confinement strategies.

Genetic group, age at entry into confinement and at slaughter, are characteristics that have an important influence on lamb performance and carcass. The aim of this study was to evaluate the performance, carcass characteristics and non-carcass components from different genetic groups (Santa Inês and ½ Dorper x ½ Santa Inês) sheep, submitted to different feedlot entry and exit strategies. Were used 72 lambs males and castrated; 36 Santa Inês (SI) and 36 crossbred (Dorper x Santa Inês-DSI), with 6 months of average initial age. The groups were established in a completely randomized experimental design, in a 2x3x4 factorial arrangement, from the combination of genetic groups (GG), body weight at the beginning of confinement (WBC) and length of stay in confinement (LSC). The body weight classes at the beginning of confinement were: light (25 kg), intermediate (28 kg) and heavy (31 kg), for Santa Inês and crossbreeds, respectively. Slaughters were carried out every 28 days of confinement, in four LSC: 0, 28, 56 and 84 days. The GG did not influence performance, carcass and non-carcass component traits of lambs (p > 0.05). There was an effect of the WBC on the weights: final (FW), metabolic (MW), body at slaughter (BWS), empty body (EBW), hot carcass (HCY) and cold (CCW), loin, shoulder, leg musculature; loin eye area (LEA) and loin fat (p < 0.05). There was also an effect on LSC, for FW, average daily weight gain (ADG), MW, weight and yield of body components, weight of cuts and tissue ratio components of cuts (p < 0.05). In non-carcass components, effect on full and empty weight of: omasum, rumen-reticulum, small intestine; empty large intestine, liver and kidneys, paws and skin, and perirenal, pelvic and inguinal fat (p < 0.05). Interaction double effect on the tissue muscle/fat:bone ratio (MF:B) and for the full omasal component (p < 0.05). And triple interaction effect for ADG, full omasum and perirenal fat (p < 0.05). Weight at the beginning of confinement and confinement time are the characteristics that most influence performance, quantitative characteristics of carcass and non-carcass components. Regardless of the genetic group and age class, the animals reach the same weight after 84 days of confinement. Thus, the confinement of heavier lambs (31 kg) can be a profitable alternative, as they presented the highest weights for the most commercially valued cuts (shank and loin). The confinement strategy must adapt to market situations.

Overnutrition of Ewe in Late Gestation and the Impact on Placental Efficiency and Lamb's Performance.

The objective of the study was to evaluate energy or energy/protein supplementation in the ewe diet, in the last third of gestation, on maternal placental and endocrine characteristics, as well as its effects on the behavior of neonatal lambs and productive performance until weaning. A total of 128 ewes were used, and the experimental diet was fed from 100 days gestation until lambing, with the birth of 172 lambs. The ewes were distributed into three treatments: CTL (control, n = 43) with metabolizable energy (ME) and crude protein (CP) intake according to NRC (1985); ME (energy supplementation, n = 44) plus 21% ME; and MECP (energy/protein supplementation, n = 41) plus 26% ME and CP. Body weight, body condition score, serum hormone concentrations, placental characteristics, lamb performance and behavior, and production efficiency of the ewe from lambing to weaning were measured. ME and MECP ewes were heavier before (p = 0.006) and just after lambing (p = 0.002) and had higher serum triiodothyronine (p = 0.001) and cortisol (p = 0.004) concentrations on the day of lambing. ME ewes had higher placental efficiency (p = 0.036) and lower total cotyledon weight (p = 0.011). ME and MECP diets increased both lamb birth weight (p = 0.015) and weaning weight (p = 0.009). Production efficiency at birth and at weaning was not influenced (p > 0.05) by treatments. Lamb behavior was influenced by the ME and MECP diets, reducing the time to kneel (p ≤ 0.05), to try to stand (p ≤ 0.05), and the latency to stand (p ≤ 0.005). It is concluded that overnutrition in the last third of gestation was positive for the ovine production system, with improved production rates, hormonal profile, placental characteristics, and neonatal behavior.