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

Abstract

In sheep production systems based on extensive grazing, neonatal mortality often reaches 15% to 20% of lambs born, and the mortality rate can be doubled in the case of multiple births. An important contributing factor is the nutrition of the mother because it affects the amount of colostrum available at birth. Ewes carrying multiple lambs have higher energy requirements than ewes carrying a single lamb and this problem is compounded by limitations to voluntary feed intake as the gravid uterus compresses the rumen. This combination of factors means that the nutritional requirements of the ewe carrying multiple lambs can rarely be met by the supply of pasture alone. This problem can overcome by supplementation with energy during the last week of pregnancy, a treatment that increases colostrum production and also reduces colostrum viscosity, making it easier for the neonatal lamb to suck. In addition, litter size and nutrition both accelerate the decline in concentration of circulating progesterone that, in turn, triggers the onsets of both birth and lactogenesis, and thus ensures the synchrony of these two events. Furthermore, the presence of colostrum in the gut of the lamb increases its ability to recognize its mother, and thus improves mother-young bonding. Most cereal grains that are rich in energy in the form of starch, when used as supplements in late pregnancy will increase colostrum production by 90% to 185% above control (unsupplemented) values. Variation among types of cereal grain in the response they induce may be due to differences in the amount of starch digested post-ruminally. As a percentage of grain dry matter intake, the amount of starch entering the lower digestive tract is 14% for maize, 8.5% for barley and 2% for oats. Supplements of high quality protein from legumes and oleiferous seeds can also increase colostrum production but they are less effective than cereal grains. In conclusion, short-term supplementation before parturition, particularly with energy-rich concentrates, can improve colostrum production, help meet the energy and immunological requirements for new-born lambs, and improve lamb survival.

Invited review: Improving neonatal survival in small ruminants: science into practice

“…Colostrum contains fat (7% to 13%), non-immunoglobulin protein (4% to 10%) and lactose (2% to 5%), and provides 6 to 7 kJ of energy/ml (Nowak and Poindron, 2006;Banchero et al, 2015). At 18°C to 26°C, lambs require 50 ml colostrum/kg within the first 18 h of life to make up for lipid energy deficit and prevent hypothermia, at 0°C to 10°C requirements increase to 280 ml colostrum/kg.…”

“…Colostrum yield is dependant on adequate supplies of both energy and protein in the last 3 weeks of gestation. Although twin-bearing ewes generally yield more colostrum than single-bearing ewes, their onset of lactation is slower and they do not produce as much colostrum per lamb (Banchero et al, 2015). Thus, multiple-born lambs, compared with singles, are disadvantaged, in addition to lower birthweights and energy reserves, and higher surface area/BW ratios.…”

“…Thus, multiple-born lambs, compared with singles, are disadvantaged, in addition to lower birthweights and energy reserves, and higher surface area/BW ratios. Inadequate nutrition during gestation can delay the onset of lactogenesis, reduce colostrum and milk production, and affect colostrum viscosity (Banchero et al, 2015). As a consequence, delayed suckling may lead to energy reserves being exhausted within 6 h of birth and result in depressed heat production.…”

Review: nutritional and endocrine control of colostrogenesis in swine

“…Circulating concentrations of progesterone can be influenced by the level of feeding. Indeed, in gilts and ewes, progesterone concentrations were reduced with a high feeding level, likely because of an increase in metabolic clearance rate (Banchero et al, 2015). Supplementing ewes with energy during the last week of pregnancy accelerates the decline in circulating progesterone that, in turns, increases colostrum yield (Banchero et al, 2015).…”

“…Indeed, in gilts and ewes, progesterone concentrations were reduced with a high feeding level, likely because of an increase in metabolic clearance rate (Banchero et al, 2015). Supplementing ewes with energy during the last week of pregnancy accelerates the decline in circulating progesterone that, in turns, increases colostrum yield (Banchero et al, 2015). However, increasing sow feed intake for the last 2 weeks of pregnancy did not affect circulating concentrations of progesterone and piglet weight gain during the first 2 days postpartum, indicating that colostrum yield was unaltered (Miller et al, 2004).…”