Luigi Francis Lima Cavalcanti

Produção e composição do leite de ovelhas Santa Inês e mestiças Lacaune e Santa Inês e desenvolvimento de seus cordeiros

Na ovinocultura, a raca Santa Ines, amplamente explorada no territorio brasileiro, possui indices de producao compativeis com sistemas europeus de exploracao leiteira (Susin et al., 2005), e o bom desempenho de animais na fase de cria esta diretamente relacionado com a producao de leite das maes (Peeters et al., 1992). A raca Lacaune tem sua origem atrelada a producao de animais de boa carcaca em diversas regioes da Franca e passou por um programa de melhoramento genetico que resultou em aumento da producao de leite e melhora da composicao da carcaca dos cordeiros destinados ao abate (Barillet et al., 2001). O presente trabalho teve o objetivo de avaliar a producao e a composicao do leite de tres genotipos de ovelhas Santa Ines, ½ Lacaune x ½ Santa Ines e ¾ Lacaune x ¼ Santa Ines ? e o desenvolvimento de seus cordeiros durante os quatro primeiros meses de lactacao.

The evolution and evaluation of dairy cattle models for predicting milk production: an agricultural model intercomparison and improvement project (AgMIP) for livestock

The contemporary concern about anthropogenic release of greenhouse gas (GHG) into the environment and the contribution of livestock to this phenomenon have sparked animal scientists’ interest in predicting methane (CH4) emissions by ruminants. We contend that improving the adequacy of mathematical nutrition model estimates of production of meat and milk is a sine qua non condition to reliably determine ruminants’ worldwide contribution to GHG. Focusing on milk production, we address six basic nutrition models or feeding standards (mostly empirical systems) and five complex nutrition models (mostly mechanistic systems), describe their key characteristics, and highlight their similarities and differences. We also present derivative systems. We compiled a database of milk production information from 37 published studies from six regions of the world, totalling 173 data points: 19 for Africa, 45 for Asia, 16 for Europe, 12 for Latin America, 44 for North America and 37 for Oceania. Four models were used to predict milk production in lactating dairy cows, and the adequacy of their predictions was measured against the observed milk production from our database. Even though these mathematical nutrition models shared similar assumptions and calculations, they have different conceptual and structural foundations inherent to their intended purposes. A direct comparison among these models was further complicated by the different models requiring unique inputs that are very often not available, and the low reliability of the inputs prevents an unbiased assessment of the model predictions. Very few studies have collected the necessary information to run more mechanistic systems, and users have to rely on standard information to populate many model inputs. Study effect was a critical source of variation that limited our ability to conclusively evaluate the models’ applicability under different scenarios of production around the world. Only after study variation was removed from the database did the adequacy of the model predictions of milk production improved, but deficiencies still existed. On the basis of these analyses, we conclude that not all models were suitable for predicting milk production and that simpler systems might be more resilient to variations in studies and production conditions around the world. Improving the predictability of milk production by mathematical nutrition models is a prerequisite to further development of systems that can effectively and correctly estimate the contribution of ruminants to GHG emissions and their true share of the global warming event.

Morfologia dos pré-estômagos e de papilas ruminais de cordeiras Santa Inês em crescimento submetidas a dois planos nutricionais

For the evaluation of nutritional schemes and change on the pre-stomach morphology and quantification of rumen papillae, 36 Santa Ines female lambs were submitted to two nutritional schemes (ad libitum or restrict) and slaughtered with different live weights (20, 30 or 40 kg) in a completely randomized factorial design 2x3. After slaughter, the viscera were weighed empty and their volume was measured. Samples of ruminal wall from the cranial and ventral sacs were collected and with a stereomicroscope photographed and analyzed regarding height, basal width, area, papillae per cm² and absorptive area per cm². The results were submitted to analyses of variance and the means were compared by Student Newman Keuls test. The different nutritional schemes did not influence the weight of rumen, reticulum or omasum (P>0.05), although, growth of the viscera was observed by increase in live weight. The viscera volume was affected by live weight, and smaller volume was observed in the animals fed ad libitum diet (P<0.10). The number of papillae per cm² was reduced by the increase in live weight. Height and area of papillae were larger in heavier animals. The nutritional scheme only affected height and area of papillae of the cranial sac. The absorptive area was not affected by the treatments. Different nutritional schemes and live weights affect the pre-stomach morphology of Santa Ines female lambs.

The development of the gravid uterus of Santa Inês ewes and ewe lambs under two nutritional planes

The Santa Ines is the most common ovine breed in Brazil, and there is a lack of information about the nutrient requirements for this genotype. As a result of the inhospitable environment where this breed was established, the metabolism of these animals evolved different strategies to reserve and utilize nutrients which may influence its requirements. The most significant drain of nutrients of pregnant ewes is the gravid uterus (GU) mainly during the last third of gestation because of the increased fetus growth rate (Rattray et al., 1974). The objective of this study was to measure the weight and composition of the GU of Santa Ines ewes and ewe lambs (primiparous ewes).