Feed intake affects metabolic clearance rate of progesterone in sheep

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.

Section: Mechanism By Which Nutrition Influences Colostrum Productionmentioning

confidence: 99%

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

Banchero

Milton

Lindsay

et al. 2015

“…However, the increase in plasma progesterone in pregnant ewes drinking water containing 1.3% sodium chloride, particularly those carrying twins, could be due to changes in the metabolic clearance of progesterone via the liver and associated drop of food intake. In non-pregnant sheep, feed intake is inversely related to plasma progesterone concentrations probably because of changes in hepatic portal blood flow and the resulting clearance rate of progesterone (Williams and Cumming, 1982;Parr et al, 1993a and1993b).…”

Section: Digby Chadwick and Blachementioning

confidence: 99%

Salt intake and reproductive function in sheep

Digby

Chadwick

Blache

2011

Producers have the possibility to combat human-induced dryland salinity by planting salt-tolerant plants such as saltbush. Saltbush has the potential to be used as a source of food for livestock at a time and place where pasture is not viable. However, saltbush contains high concentrations of sodium chloride salt and some other anti-nutritional factors that have the potential to affect feed and water intake and, directly or indirectly, the reproductive capacity of sheep. High-salt diet during gestation induces a small modification of the activity of the renin-angiotensin system (RAS) that has an important role in the maintenance of the salt-water balance in non-pregnant and pregnant sheep. In contrast, the main effect of salt ingestion during pregnancy is observed on the biology of the offspring, with changes in the response of the RAS to salt ingestion and altered thirst threshold in response to an oral salt ingestion. These changes, observed later in life, are the result of fetal programming following the ingestion of salt by the mother. It seems that the exposure to salt during pregnancy could provide an advantage to the offspring because of this adaptive response. The response may be particularly useful, for example, when grazing herbivores are fed halophytic forages adapted to saline soils.

“…Increasing dietary intake has been shown to reduce peripheral progesterone concentrations. It has been concluded that high feed intake increases liver blood flow and metabolic clearance, which leads to lowered plasma progesterone concentration (Parr et al, 1993a and1993b). These diet-induced alterations are mediated by insulin signalling (Smith et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Fertility and growth of nulliparous ewes after feeding red clover silage with high phyto-oestrogen concentrations

Mustonen

Taponen

Andersson

et al. 2014

The study aimed to determine the effects of red clover (Trifolium pratense) silage with high phyto-oestrogen content on ewe performance during their first breeding season. Red clover silage containing formononetin, biochanin A, genistein, and daidzein was fed to 10 nulliparous ewes of the prolific Finnish Landrace breed before, during and after the breeding season, for a total of 5 months. A control group of 10 ewes was fed with grass silage. The mean numbers of foetuses per pregnancy were 2.1 ± 0.7 and 2.2 ± 0.8 for the red clover and control groups, respectively. The total mass of the uterus with its contents was significantly greater in ewes of the red clover group compared with those of the control group. This difference was mainly explained by the greater volume of foetal fluids. Serum progesterone concentration in the red clover group was significantly lower over the entire period analysed than in the control group. In conclusion, the fecundity of the ewes was not reduced by red clover feed with high phyto-oestrogen concentrations. The volume of foetal fluids increased that could increase the risk for vaginal prolapse before the term.Keywords: ewe, red clover, phyto-oestrogen, formononetin, equol ImplicationsThe symbiotic rhizobia bacteria in red clover can fix atmospheric nitrogen, which promotes the growth of red clover itself and subsequent crops. This ability makes red clover valuable crops, especially in organic agriculture. Red clover is also a valuable ruminant feed, for example, lambs fed with red clover grow very well. Red clover is a rich source of polyphenols such as isoflavones, also referred to as phyto-oestrogens. Phyto-oestrogens can cause infertility problems in animals. As organic farming and the use of red clover is ever increasing, it is important to study what effect red clover feeding has on ewes' reproduction.