The effect of nutritional supplements in late pregnancy on ewe colostrum production plasma progesterone and IGF-1 concentrations

Abstract

Mechanisms by which nutritional supplementation might improve colostrum production and enhance lamb survival were examined in adult Border LeicesterxMerino ewes. Ewes were either unsupplemented or supplemented with 500 g/day of oat grain, lupin grain or a formaldehyde-protected sunflowerseed meal (SFM) from day 130 of gestation until parturition while grazing spring pastures containing about 1000 kg green DM/ha. Blood samples were obtained on day 140, day 145 and immediately after parturition. Colostrum production at parturition and for the next 6 h was determined. A new method to determine concentrations of insulin-like growth factor-1 (IGF-1) is presented. Colostrum production at parturition (P.< 0.01) and IGF-1 concentration on day 140 (P.< 0.01) and at parturition (P.< 0.001) were higher, and progesterone concentrations on days 140, 145 and at parturition were lower (P.< 0.001) for single than twin bearing ewes. The unsupplemented ewes and ewes fed oat grain, lupin grain or SFM had an average weight of colostrum at parturition of 292, 328, 452 and 392 g (P.< 0.01), milk secretion rate to 6 h after parturition of 58, 64, 85 and l00g DM/h (P.< 0.05), IGF-1 concentrations after parturition of 199, 223, 262 and 265 ng/mL (P.< 0.001) and progesterone concentrations on day 140 of 49, 43, 39 and 41 nmol/L (P.< 0.01) respectively. Twin compared to single bearing ewes had about half the amount of colostrum at parturition per kg of lamb birthweight. Progesterone concentrations on day 140 and at parturition (P.< 0.01) were negatively related to estimated pasture intake during pregnancy, which was 17% higher for single than twin bearing ewes (P.< 0.05). Supplementation with lupins and SFM may be expected in similar circumstances to enhance the survival of multiple born lambs, while oat grain would not.

Colostrum production in ewes: a review of regulation mechanisms and of energy supply

“…The increase in colostrums output in supplemented ewes ranged from 90% to 185% over that of unsupplemented ewes. However, Hall et al (1992a) and Holst et al (2005) did not detect any increase in colostrum production in Merino ewes supplemented with oats, suggesting that oats did not have the same effects on colostrum production as the other cereals evaluated. The reasons for this difference will be discussed below.…”

“…Moreover, although ewes may be able to consume enough DM at the end of pregnancy, it would not be enough to meet their requirements for lactogenesis (Ministry of Agriculture, Fisheries and Food (MAFF), 1975) if this DM was obtained from native pastures. Normally, these pastures have a heterogeneous distribution of species and quality varied during and between years (low protein: <100 g/kg of DM and low ME: <8.5 MJ/kg of DM of forage; Bermúdez and Ayala, 2005) For these reasons, researchers investigated the value of short-term supplementation of the ewe under grazing conditions at the end of pregnancy (Hall et al, 1992a and1992b;Murphy et al, 1996;Roeder et al, 2000;Banchero et al, 2004aBanchero et al, and 2004bBanchero et al, , 2007Banchero et al, , 2009Holst et al, 2005;Fierro et al, 2012;Hawken et al, 2012). Supplements like cereal grains or concentrates would provide high energy/protein in a small volume of feed.…”

“…Hall et al (1992a), working with Border Leicester × Merino ewes, found that supplementation with lupin grain (Lupinus angustifolius) or formaldehyde-protected sunflower seed meal at 500 g/day during the last 2 weeks of pregnancy increased colostrum output by 35% and 50%. In this experiment, single-bearing ewes produced similar amounts of extra colostrum with either supplement, but twin-bearing ewes produced more colostrum only when supplemented with sunflower seed meal.…”

“…The importance of protein The increase in colostrum production after feeding supplements of legumes and oleiferous seeds (lupins and sunflower seed meal) is mainly related to their high protein content, especially their ability to supply undegraded protein to the small intestine (Hall et al, 1992a). In contrast, excess protein has been shown to either have no effect or to decrease colostrum production (Ocak et al, 2005).…”

A pre-partum lift in ewe nutrition from a high-energy lick or maize or by grazing Lotus uliginosus pasture, increases colostrum production and lamb survival

“…The extra colostrum produced by the ewes in these studies should have improved the likelihood of their lambs surviving, but lamb survival was not measured. Hall et al, (1992) reported an increase in colostrum production from single but not twinbearing ewes supplemented with a concentrate containing by-pass protein that would increase the supply of protein for digestion to amino acids in the small intestine. Lotus uliginosus, a high protein legume containing tannins, could also provide additional protein for digestion to amino acids in the small intestine of ewes bearing single lambs.…”