Effect of the Dietary Royal Jelly Supplementation in Ewes of Bulgarian Dairy Synthetic Population on the Body Weight of the Lambs and the Milk Composition

Abstract

The aim of the experiment was to assess the effect of the royal jelly supplementation in the diet of ewes from Bulgarian Dairy Synthetic Population on the body weight of the lambs and the milk composition. The trial was carried out with 20 ewes and their lambs, reared in the experimental sheep farm of the Institute of Animal Science- Kostinbrod, Bulgaria and lasted 30 days during the suckling period. The animals had the same date of lambing and lambs’ body weight, and were divided into two groups, each containing 10 ewes. The feeding was according to the standards for this category of ruminants with ad libitum access to water, as each ewe from the supplemented group received twice a week 300 mg freeze dried royal jelly. The body weight of the lambs was controlled at the beginning and at the end of the trial period, and the weight gain was calculated. The chemical and the fatty acid composition of the milk was measured in individual samples. The fatty acid composition was used to calculate the atherogenic (AI) and thrombogenic (TI) indices. The live weight (LW) and the average daily gain (ADG) differed between the groups of lambs according to the dietary royal jelly supplementation. The lambs of the ewes that had received the supplement displayed higher LW (P=0.0138) and ADG (P=0.0062). The physicochemical composition of the milk showed lower fat content (P=0.0142) and higher density (P=0.0200) in the ewes receiving royal jelly. Significant increase of C18:0 and decrease of C17:1 proportion was observed. Additionally, the contents of the polyunsaturated С20:4n-6, С22:5n-3 and C22:6n-3 was considerably diminished in the milk of the group that received royal jelly. The results so far demonstrated the potential of the royal jelly to manipulate the fatty acid profile of the ewes’ milk.