Altering ewe nutrition in late gestation: I. The impact on pre- and postpartum ewe performance1

Abstract

The present study was conducted to examine the effects of offering a single diet rationed to 80% (80% ME), 100% (100% ME), or 120% (120% ME) of recommended ME requirements from d 119 of gestation to lambing, with concurrent changes in other dietary nutrients. The effects on pre- and postpartum ewe performance, including estimated milk yield and milk fatty acid concentrations, were monitored. Sixty twin-bearing ewes were allocated to 1 of 3 dietary treatments ( = 20 per treatment) and individually fed for the final 4 wk of gestation. Metabolizable energy requirements were individually calculated for each ewe and amended according to treatment. Ewes were rationed daily on the basis of their treatment ME allocation, which led to concurrent alterations in other nutrient intakes. Diets were grass silage based and supplemented with concentrates to meet treatment ME allocation on an individual ewe basis. Ewes offered the 80% ME treatment had a lower liveweight ( = 0.04) and BCS ( = 0.03) at 24 h postpartum when compared with ewes offered the 120% ME diet. Although there was no difference in liveweight at either d 40 ( = 0.18) or 98 postpartum ( = 0.20), the difference in BCS persisted until d 40 postpartum ( = 0.02). Colostrum yield at 1 h postpartum ( = 0.03) and total yield up to 18 h postpartum ( = 0.04) was greater for ewes offered the 120% ME diet than either of the other treatment groups. Similarly, these ewes had a greater estimated milk yield during wk 3 of lactation ( = 0.04) and elevated concentrations of short-chain SFA ( = 0.02) and long-chain SFA ( ≤ 0.05) from wk 2 through 6 of lactation. In summary, the negative impact of applying a dietary insult to ewes in late gestation is reflected in colostrum and estimated milk yield and fatty acid composition, thus potentially influencing postpartum growth and development of the offspring.

Altering ewe nutrition in late gestation: II. The impact on fetal development and offspring performance1

“…Previous studies have demonstrated the utilization of body fat reserves by the ewe to preserve circulating concentrations of glucose during periods of nutrient restriction, thus maintaining fetal growth (Tygesen et al, 2008). This is supported, in the present study, by a marked reduction in BCS between ewes allocated to the restricted and excessive energy treatments (McGovern et al, 2015) coupled with the lack of difference seen in blood glucose concentration, organ size and, ultimately, birth weight of the offspring. It may be that the ewe yielded her own body reserves to ensure optimal fetal growth during the final stage of gestation.…”

“…Studies have outlined the influence of both maternal BCS and gestational nutrition on lamb birth weight (Gardener et al, 2005;Kenyon et al, 2009;Caton and Hess, 2010;Meyer et al, 2010), highlighting its importance in the detection of fetal growth restriction and/or adequate maternal nutrition. In the present study, despite the difference in ewe DMI and BCS (McGovern et al, 2015), there was a lack of difference observed in lamb birth weight. Initially, this highlighted the apparent adequacy of nutrition received by the ewes on each of the 3 dietary treatments and contradicted the earlier findings of Russel et al (1977), who reported that a moderate degree of undernourishment in late gestation resulted in the reduced weight of twin lambs at birth.…”

“…On d 119 of gestation, ewes were housed in individual pens with 33 ewes penned on wooden slats and the remaining 27 ewes penned on expanded metal slats with floor type balanced across treatments. A detailed description of the feeding management and the data collection of the ewes for the final 4 wk of gestation and at lambing is provided in a companion manuscript (McGovern et al, 2015). The chemical composition of feedstuffs offered is outlined in Table 1.…”

“…The management of ewes from mating until d 105 of gestation is detailed in a companion paper (McGovern et al, 2015). Six weeks before the mean predicted lambing date, 60 mature twin-bearing ewes were selected for this study and were randomly allocated to 1 of 3 nutritional treatments (n = 20 per treatment).…”

“…Lamb plasma samples were analyzed for glucose (interassay CV = 0.20), NEFA (mmol/L), urea (mmol/L), and total protein (g/L) content as outlined in a companion paper (McGovern et al, 2015).…”