Milk yield, milk composition and reproductive performance of Santa Inês ewes fed diets containing canola or linseed oil

The objective in this study was to evaluate the effect of the addition of canola oil (CO) or linseed oil (LO) on milk production and composition and reproductive performance of Santa Inês ewes. In the experiment I, 33 Santa Inês ewes were fed diets containing 50% of roughage (Cynodon dactylon hay). Experimental diets included a control (no oil) and two remaining diets with the addition of 3% of CO or LO (dry matter basis). Ewes were mechanically milked once a week and milk production, in a 3 hours interval, was recorded and sampled for composition and fatty acid (FA) profile determination. The addition of oils decreased DM intake and incresead serum non-esterified FA concentration. Lamb performance, milk yield and chemical composition were not altered by the diets. Feeding oils decreased short and medium chain FA, saturated FA (SFA), 9-dessaturase enzyme activity and atherogenicity index; and increased C18:0, C18:1 n-9, C18:2 cis-9, trans-11 C18:2 (CLA), C18:1 trans-11, C18:3 n-3, long chain, mono and polyunsaturated FA (PUFA) in milk fat. In addition, both oils improved FA profile of milk fat, and LO increased the concentration of healthier FA (trans-11 C18:1, cis-9 trans-11 CLA, total CLA and n-3 FA). In the experiment II, 222 Santa Inês ewes were assigned, according to body weight (BW) and body condition score, to one of three experimental diets to determine the effects of fat sources on pregnancy and estrus index, BW, time to estrus and number of lambs per ewe. Ewes were fed diets containing 40% of sugarcane bagasse as the roughage source and the experimental diets included a control (no oil) and two remaining diets with the addition of 3% of CO or LO (dry matter basis). All ewes were fed the experimental diets 45d before the estrus synchronization. The synchronization protocol consisted on vaginal insertion of a progesterone (P4) device for 5d (D0), rams introduction, i.m. injection of eCG (1.5 mL) and PGF2 (2.0 mL) on the 5th day (D5). At D0 the ewes BW was obtained. The time of P4 device withdrawal (D5) was recorded and estrus observation lasted 72 hours. The 2nd service began at D16 and lasted 13 days. The BW and number of lambs per ewe were not affected by diets. The rates of onset of estrus, pregnancy at 1st and 2nd services and time for the onset of estrus were not affected by diets. The total pregnancy rate was higher in animals from the control diet compared to those fed LO. Supplementation of oil rich in oleic acid or linolenic acid did not improve reproductive rates of Santa Inês ewes. (AU)