The effect of constant dietary energy supply during late gestation and early lactation on performances of prolific D’man ewes

A total of 42 prolific D’man ewes were used to study the effect of the dietary energy supply on their performances during the last 45 days of pregnancy and the first 60 days of the suckling phase. The ewes were fed 1 kg of hay and supplemented with either 200 (treatment L), 570 (treatment M) or 840 g (treatment H) of a barley and soyabean-based concentrate. The proportion of soyabean was adjusted so that the crude protein (CP) content of the three diets was similar (120 g CP·kg–1). The energy contents of the diets were 1.2, 1.8 and 2.2 of the daily net energy requirements for maintenance in respectively the L, M and H treatments. Daily hay intake averaged 829 ± 18 g dry matter (DM) per ewe and was not affected by the level of the concentrate distributed. The body condition score of the ewes in all treatment groups was low at the beginning of the experiment (1.9 ± 0.3) and continued to decline throughout the period of treatment application. Nevertheless, the rate of decline was higher for the L and M ewes (P < 0.05). The live weight of the ewes after lambing was higher (P < 0.05) for ewes in the H treatment group (43.2 ± 6.9 kg) in comparison to the other ones (37.7 ± 7.8 and 40.0 ± 7.3 kg for the L and M groups respectively). Daily milk production over the first 40 days of lactation (959 ± 399 g·day–1) was not affected by the energy level of the diet. Similarly, fat (8.9 ± 2.4%) and protein (4.5 ± 0.9%) contents of the milk were not affected by the diet energy content. The weights of the lambs at birth, at 10, 30 and 50 days of age were not influenced by the diet energy content. In contrast, average daily growth (ADG) between 10 and 30 (ADG10–30) and also between 30 and 50 days of age (ADG30–50) were significantly affected by energy allowances in the diet (95 ± 23, 133 ± 25, and 152 ± 27 g·day–1 for ADG10–30 and 76 ± 22, 135 ± 24 and 136 ± 24 g·day–1 for ADG30-50 in L, M and H groups respectively). It is concluded that the energy requirements of prolific D’man ewes during late gestation and early lactation are likely to be higher than the levels attempted in this study.Effet du niveau énergétique de la ration sur les performances de la brebis prolifique D’man en fin de gestation et début de lactation. Quarante deux brebis de la race prolifique D’man ont été utilisées pour étudier les effets du niveau énergétique de la ration sur leurs performances de production pendant 45 j en fin de gestation et 60 j après la mise-bas. Les brebis ont reçu 1 kg de foin complémenté avec 240 g (lot bas : B), 570 g (lot moyen : M) ou 840 g (lot haut : H) d’un concentré à base d’orge et de tourteau de soja. La proportion de ce dernier a été ajustée pour obtenir 3 rations iso-azotées (120 g MAT·kg–1). Les apports énergétiques sont estimés à 1,2, 1,8 et 2,2 fois le besoin d’entretien pour les lots L, M et H respectivement. L’ingestion du foin (829 ± 18 g MS·j–1) n’est pas affectée par la quantité de concentré distribuée. La note d’état corporel des brebis est très faible au début de l’essai (1,9 ± 0,3) et continue à baisser tout au long de l’expérience. Cependant, la baisse est plus prononcée (P < 0,05) chez les brebis qui reçoivent les niveaux L et M. Le poids vif des brebis après la mise-bas est aussi affectée (P < 0,05) par le niveau énergétique de la ration (37,7 ± 7,8, 40,0 ± 7,3 et 43,2 ± 6,9 kg pour les lots L, M et H respectivement). La production laitière (959 ± 399 g·j–1), les teneurs en matière grasse (8,9 ± 2,4 %) et protéique (4,5 ± 0,9 %) ne sont pas influencées par le niveau énergétique de la ration. Les poids à la naissance, à 10, 30 et 50 j sont similaires pour les trois traitements. En revanche, les gains moyens quotidiens entre 10 et 30 j (GMQ10–30) et entre 30 et 50 j (GMQ30–50) sont significativement (P < 0,05) améliorés par l’accroissement du niveau énergétique de la ration (95 ± 23, 133 ± 25 et 152 ± 27 g·j–1 pour GMQ10–30 et 76 ± 22, 135 ± 24 et 136 ± 24 g·j–1 pour GMQ30–50 respectivement dans les lots L, M et H). Il est conclu que les besoins énergétiques des brebis prolifiques D’man sont vraisemblablement plus élevés que les niveaux testés dans cet essai

Live Weight Changes and Their Relationship with the Ovarian Status of Maiden Fat-Tailed Barbarine Ewes

The current study assessed the effect of the pattern of live weight change on the ovarian function of maiden Barbarine ewes at approximately 1 year of age. For this purpose, a total of 171 weaned ewe lambs (mean live weight  ± s.d. 34.7±3.07 kg and mean age ± SD 196±10 days at weaning) were selected for the experiment. Adjustment of live weight variation  was used. Based on the slope of the curve, animals were grouped into three classes LWCI (n=46),  LWCII (n=91) and LWCIII (n=34) with live weight loss being highest in LWCI and lowest in LWCIII.  Following laparoscopy at 13 months of age, the proportion of ewe lambs found cycling in LWCIII  (85.3%) was higher in comparison to animals in LWCI (43.4%; P&lt;0.001) and tended to be superior to those in LWCII (61.5%; P&lt;0.05). Following synchronisation with progestagen of the females found cycling, levels of plasma IGF-I concentrations between 6 and 42 hrs after removal of sponges were not significantly different between the three classes of live weight, and respectively averaged 94.2, 90.8 and 89.8 µg/l for LWCI, LWCII and LWCIII females. Levels of estradiol were also not significantly different between the three groups (0.73, 0.70 and 0.67 pg/ml for LWCI, LWCII and LWCIII ewe lambs, respectively). It was concluded that, in low input systems of semi-arid and arid Tunisia, mating ewe lambs at the approximate age of 1 year is likely to lead to depressed reproductive performance particularly when the summer live weight-loss is elevated.

Live Weight Changes and Their Relationship with the Ovarian Status of Maiden Fat-Tailed Barbarine Ewes

The current study assessed the effect of the pattern of live weight change on the ovarian function of maiden Barbarine ewes at approximately 1 year of age. For this purpose, a total of 171 weaned ewe lambs (mean live weight  ± s.d. 34.7±3.07 kg and mean age ± SD 196±10 days at weaning) were selected for the experiment. Adjustment of live weight variation  was used. Based on the slope of the curve, animals were grouped into three classes LWCI (n=46),  LWCII (n=91) and LWCIII (n=34) with live weight loss being highest in LWCI and lowest in LWCIII.  Following laparoscopy at 13 months of age, the proportion of ewe lambs found cycling in LWCIII  (85.3%) was higher in comparison to animals in LWCI (43.4%; P<0.001) and tended to be superior to those in LWCII (61.5%; P<0.05). Following synchronisation with progestagen of the females found cycling, levels of plasma IGF-I concentrations between 6 and 42 hrs after removal of sponges were not significantly different between the three classes of live weight, and respectively averaged 94.2, 90.8 and 89.8 µg/l for LWCI, LWCII and LWCIII females. Levels of estradiol were also not significantly different between the three groups (0.73, 0.70 and 0.67 pg/ml for LWCI, LWCII and LWCIII ewe lambs, respectively). It was concluded that, in low input systems of semi-arid and arid Tunisia, mating ewe lambs at the approximate age of 1 year is likely to lead to depressed reproductive performance particularly when the summer live weight-loss is elevated

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