Performance of the fat-tailed Barbarine sheep in its environment: adaptative capacity to alternation of underfeeding and refeeding periods. A review

The Barbarine sheep is characterised by a fat-tail, whose mass varies between 1 and 4 kg. Its management is traditionally based on spring mating. The ability of this fat-tailed ewe to mobilise its body reserves has been demonstrated in lactation and the dry period by experimentally varying the food supply. The severely underfed ewe (200 g oat hay) can survive 161 days and lose 36% of its body weight (BW), with a change of 8.8 kg of dissected adipose tissue (AT) and 3.4 kg of muscle. It reached this stage with an empty BW of 24 kg containing 12% of AT. The fat tail exerts a role as a body reserve mainly through its mass rather than through its ability to be rapidly mobilised. In such situations, plasma NEFA and 3-hydroxybutyrate concentrations are first almost doubled, then decline in permanently underfed ewes, showing the ability of Barbarine ewes to adjust their lipid metabolite concentration in order to limit the toxic effects of high concentrations and therefore prolong survival. By the end of a re-feeding period, Barbarine ewes returned to their initial BW, lipid and protein mass. This breed has a good fertility, which can, however, be depressed in cases of undernutrition. However, if the mating period is extended, the overall reproductive performance is generally satisfactory. Poor nutrition during pregnancy may reduce lamb birth weight and affect subsequent growth, however, in traditional conditions, ewe and lamb mortality rates are surprisingly low in this breed. In normal birth weighted lambs, the post-weaning growth performances of grazing lambs are moderate but in feedlot conditions the conversion rate is rather low and carcass adiposity is high. This review shows that the Barbarine sheep, and specially the ewe, is well adapted to the local conditions mainly because of its high fertility and its ability to deposit and mobilise body reservesLa race Barbarine est caractérisée par une queue grasse dont la masse varie de 1 à 4 kg. Le système traditionnel d’élevage de la Barbarine est basé sur la lutte de printemps. La capacité de mobilisation des réserves chez cette brebis a été démontrée, aussi bien sur brebis allaitantes que sur brebis taries,en faisant varier expérimentalement les apports alimentaires. Des brebis sévèrement sous-alimentées(200 g de foin d’avoine par j) survivent 161 jours en perdant 36 % de leur poids vif initial (PV), avec8,8 kg de tissus adipeux (TA) et de 3,4 kg de muscle. Elles atteignent cet état avec un PV vide de24 kg contenant 12 % de TA. Le gras caudal agit comme réserve corporelle plutôt par sa masse que par son aptitude à être mobilisé rapidement. Dans de telles conditions, les concentrations plasmatiques en AGNE et 3-hydroxybutyrate sont transitoirement doublées puis elles déclinent, chez les brebis toujours sous-alimentées, montrant la capacité de la Barbarine à ajuster la concentration des métabolites lipidiques pour limiter les effets toxiques des fortes concentrations et prolonger la survie. En fin de période de réalimentation, les brebis Barbarine retournent à leur PV et masses lipidique et protéique initiales. Cette race a une fertilité satisfaisante, qui peut diminuer en cas de sous-nutrition. Cependant, si la période de lutte est suffisamment longue, la fertilité s’améliore. La sous-nutrition durant la gestation peut entraîner une réduction du poids des agneaux à la naissance. Cependant et dans de telles conditions, le taux de mortalité des agneaux est étonnamment faible. Chez des agneaux à poids de naissance normal, la croissance post-sevrage est modérée au pâturage mais,en bergerie, elle reste faible avec une efficacité alimentaire particulièrement basse et une adiposité élevée. Cette revue montre que la brebis de race Barbarine est bien adaptée aux conditions locales en raison de sa bonne fertilité et sa capacité à déposer et mobiliser des réserves corporelle

Pour maîtriser la reproduction

National audienc

Role of the uterus in early regression of corpora lutea induced by the ram effect in seasonally anoestrous Barbarine ewes

International audienc

The effect of short-term treatment of ewes with either intravenous glucose or a supplement of soya and maize during the luteal phase on the number of follicles and the AMPK signalling pathway in granulosa and theca cells

National audienc

Role of the uterus in early regression of corpora lutea induced by the ram effect in seasonally anoestrous Barbarine ewes

International audienc

Effects of eCG are more pronounced in primiparous than multiparous Bos indicus cows submitted to a timed artificial insemination protocol

National audienc

Male-induced short oestrous and ovarian cycles in sheep and goats: a working hypothesis

The existence of short ovulatory cycles (5-day duration) after the first male-induced ovulations in anovulatory ewes and goats, associated or not with the appearance of oestrous behaviour, is the origin of the two-peak abnormal distribution of parturitions after the “male effect”. We propose here a working hypothesis to explain the presence of these short cycles. The male-effect is efficient during anoestrus, when follicles contain granulosa cells of lower quality than during the breeding season. They generate corpora lutea (CL) with a lower proportion of large luteal cells compared to small cells, which secrete less progesterone, compared to what is observed in the breeding season cycle. This is probably not sufficient to block prostaglandin synthesis in the endometrial cells of the uterus at the time when the responsiveness to prostaglandins of the new-formed CL is initiated and, in parallel, to centrally reduce LH pulsatility. This LH pulsatility stimulates a new wave of follicles secreting oestradiol which, in turn, stimulates prostaglandin synthesis and provokes luteolysis and new ovulation(s). The occurrence of a new follicular wave on days 3–4 of the first male-induced cycle and the initiation of the responsiveness to prostaglandins of the CL from day 3 of the oestrous cycle are probably the key elements which ensure such regularity in the duration of the short cycles. Exogenous progesterone injection suppresses short cycles, probably not by delaying ovulation time, but rather by blocking prostaglandin synthesis, thus impairing luteolysis. The existence, or not, of oestrous behaviour associated to these ovulatory events mainly varies with species: ewes, compared to does, require a more intense endogenous progesterone priming; only ovulations preceded by normal cycles are associated with oestrous behaviour. Thus, the precise and delicate mechanism underlying the existence of short ovulatory and oestrous cycles induced by the male effect appears to be dependent on the various levels of the hypothalamo-pituitary-ovario-uterine axis

Male-induced short oestrous and ovarian cycles in sheep and goats: a working hypothesis

International audienc

Effects of dam age, litter size and gender on birth weight of D'man lamb -Consequence on lamb mortality-

International audienc