Effect of plane of nutrition of 1-and 2-year-old ewes in early and mid-pregnancy on ewe reproduction and offspring performance up to weaning

The objective of the present study was to determine the effect of plane of nutrition in early pregnancy (EP) and mid-pregnancy (W), on the productive performance of 1- and 2-year-old ewes and their offspring. Over 2 successive years, between days 0 and 39 after synchronized mating (EP), 1- (n=117) and 2- (n=52) year-old ewes were allowed 60% (low, L-EP), 100% (medium, M-EP) or 200% (high, H-EP) of requirements for maintenance (M). Between days 40 and 90 (MP), 1-year-old ewes were allowed 140% (M-MP) or 200% (H-MP), while 2-year-old ewes were allowed 80% (M-MP) or 140% (H-MP) of their M requirement. After day 90, all ewes were fed to meet requirements for late pregnancy. Increasing the plane of nutrition between days 0 and 39 resulted in increases in live weight (LW) (PM-EP>LEP), differences that in 1-year-old ewes were sustained to lambing (P0.05). These ewes exhibited more positive maternal behaviours (e.g. increased grooming frequency and duration, P

Nutritonal status of adult ewes during early and mid-pregnancy. 1. Effects of plane of nutrition on ewe reproduction and offspring performance to weaning

The objective of this study was to determine the effects of plane of nutrition during early and mid-pregnancy on the performance of mature ewes and their offspring. From day 0 to day 39 post mating (early pregnancy, EP), 82 multiparous ewes were fed to provide either 60% (low, L), 100% (medium, M) or 200% (high, H) of predicted metabolisable energy (ME) requirements for maintenance, following a synchronised mating. From day 40 to day 90 (mid-pregnancy, MP), ewes were provided with either 80% (M) or 140% (H) of ME requirements. After 90 days of gestation, all ewes were fed to meet requirements for late pregnancy. During EP, mean live weight (LW) and body condition score (BCS) change of ewes were -6.3, -0.8 and +6.0kg and -0.02, +0.10 and +0.22 units in the L-, M- and H-EP treatments, respectively. During MP, mean LW and BCS change were -0.8 and +4.9kg and -0.09 and +0.09 units in the M- and H-MP treatments, respectively (P 0. 05) on conception rate, although there tended to be an inverse relationship (P = 0.085) between plane of nutrition in EP and plasma progesterone concentrations at day 42 of gestation. EP nutrition influenced foetal development with lambs from ewes offered diet L-EP being smaller (P

An evaluation of the effect of altering nutrition and nutritional strategies in early lactation on reproductive performance and estrous behavior of high-yielding Holstein-Friesian dairy cows

Reproductive performance in the high-yielding dairy cow has severely decreased in the last 40 yr. The aim of this study was to compare the effectiveness of 4 nutritional strategies in improving the reproductive performance of high-yielding dairy cows. It was hypothesized that offering cows a high-starch ration in early lactation would enhance the onset of luteal activity, and that decreasing the severity of negative energy balance in the early postcalving period would improve reproductive parameters. Nutritional regimens aimed at improving fertility were applied to 96 Holstein-Friesian dairy animals. Upon calving, animals were allocated in a balanced manner to one of 4 dietary treatments. Primiparous animals were balanced according to live weight, body condition score and calving date. Multiparous animals were balanced according to parity, previous lactation milk yield, liveweight, body condition score and calving date. Treatment 1 was based on an industry best practice diet (control) to contain 170 g of crude protein/kg of dry matter. Treatment 2 was an individual cow feeding strategy, whereby the energy balance (EB) of individual animals was managed so as to achieve a predetermined target daily EB profile (+/- 10 MJ/d). Treatment 3 was a high-starch/high-fat combination treatment, whereby an insulinogenic (high-starch) diet was offered in early lactation to encourage cyclicity and followed by a lipogenic (low-starch, high-fat) diet to promote embryo development. Treatment 4 was a low-protein diet, containing 140 g of crude protein/kg of dry matter, supplemented with protected methionine at an inclusion level of 40 g per animal per day. The nutritional strategies implemented in this study had no statistically significant effects on cow fertility measures, which included the onset of luteal activity, conception rate, in-calf rate, and the incidence of atypical cycles. The individual cow feeding strategy improved EB in early lactation but had no benefit on conception rate to first insemination. However, conception rate to second insemination, 100-d pregnancy rate (from the commencement of breeding), and overall pregnancy rate tended to be higher in this group. The high-starch/high-fat treatment tended to decrease the proportion of delayed ovulations and increase the proportion of animals cycling by d 50 postcalving. Animals that failed to conceive to first insemination had a significantly longer luteal phase in the first cycle postpartum and a longer inter-ovulatory interval in the second cycle postpartum. With regards to estrous behavior, results indicate that as the size of the sexually active group increased, the intensity of estrus and the expression of mounting or attempting to mount another cow also increased. Furthermore, cows that became pregnant displayed more intense estrous behavior than cows that failed to become pregnant.