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.

Estresse calórico e reprodução em ovinos: fundamentos e perspectivas tecnológicas / Heat stress on sheep reproduction: fundamentals and technological perspectives

A ovinocultura é uma importante atividade que produz proteínas de alto valor biológico, mas seus ganhos podem ser reduzidos em função do estresse ambiental. Isso reforça a importância de se estudar a relação entre o ambiente térmico e o animal, identificando animais mais adaptados e férteis, e melhores práticas de manejo. O ovino (Ovis aries) é um animal homeotérmico, que mantem sua temperatura corporal em equilíbrio dinâmico. Quando em estresse calórico, os ovinos usam mecanismos sensíveis e latentes para dissipar o calor acumulado, com destaque para o redirecionamento do fluxo sanguíneo, a ofegação e a sudorese. O escroto desempenha importante crucial na termorregulação dos testículos, os quais precisam funcionar sob em até 6,0oC abaixo da temperatura interna corpórea. A hipertermia testicular compromete a espermatogênese, reduz a concentração seminal, a motilidade progressiva e a viabilidade espermática. Ainda, leva a aumento dos defeitos morfológicos espermáticos, na produção de espécies reativas de oxigênio e na fragmentação do DNA espermático, diminuindo a capacidade fecundante. Tecnologias disruptivas para monitoramento do ambiente de produção, da termorregulação e do bem-estar dos animais já são realidade e se encontram em expansão, favorecendo a tomada de decisões em tempo real e o desempenho reprodutivo dos ovinos.

Sheep farming is a relevant activity that provides proteins of high biological value, but its gains can be reduced due to environmental stress. This reinforces the importance of studying the relationship between the thermal environment and the animal, identifying more adapted and fertile animals, and better management practices. Sheep (Ovis aries) are homeothermic animals and thus maintain their body temperature in a state of dynamic balance. Under heat stress, sheep dissipate accumulated heat through sensitive and latent mechanisms, primarily using redirection of blood flow, panting and sweating. The scrotum plays a crucial role in the thermoregulation of the testicles, which need to be maintained up to 6.0oC below the body core temperature. Testicular hyperthermia impairs spermatogenesis, reduces seminal concentration, progressive motility and sperm viability. Furthermore, it leads to an increase in sperm morphological defects, in the production of reactive oxygen species, and in sperm DNA fragmentation, reducing the fertilizing capacity. Disruptive technologies for monitoring the production systems, animal thermoregulation and welfare are already a reality and are expanding, favoring realtime decision making and the reproductive performance of sheep.