This study aimed to analyze the chemical composition and the IgG concentration of the colostrum, transitional milk, and mature milk of Santa Inês ewes as well as the transfer of passive immunity to lambs. Thirty-two pregnant ewes and 38 lambs were used. Ewes were milked immediately after lambing and at 12, 24, 36 h and 10 d postpartum. Colostrum was provided to the lambs at 40±15 min (mean±SE) after birth and then at 30-min intervals for obtaining the intake closest to 10% of body weight, and transitional milk was provided ad libitum. Blood from the lambs was collected 36 h after birth for measuring the serum concentrations of IgG, total protein, albumin, and gamma-globulin. The production was lower in primiparous than in multiparous ewes with body condition score (BCS)<2.75, but did not differ between primiparous and multiparous with BCS≥2.75 (interaction parity and BCS). The IgG concentration and fat, protein, lactose, and defatted dry extract percentages were not affected by the BCS of the ewe at lambing or by the parity. The total solids percentage in the colostrum was higher in ewes with BCS<2.75 (interaction BCS and time). The production and the protein, total solid, and defatted dry extract percentages showed quadratic behavior, the fat percentage decreased linearly, and the lactose percentage increased linearly with time postpartum. The IgG concentration in the colostrum was not correlated with the ewe's weight or BCS at the time of lambing. Moreover, the parity, the BCS, the ewe's type of gestation, and the lamb's sex did not influence the serum concentrations of IgG, total protein, albumin, and gamma-globulin in lambs. Adequate passive immune transfer (PIT) was observed in lambs for which the IgG intake was higher than 30 g. Failure in PIT was observed in 39.5% of lambs when considering a serum IgG concentration lower than 15 mg/mL and in 21% when considering a serum total protein concentration lower than 45 mg/mL. The mean apparent efficiency of absorption was 38.10%, with values between 0.02% and 98.80%. The serum IgG concentration was correlated with the total protein concentration (according to the enzymatic colorimetric method), the gamma-globulin concentration, and the absorption efficiency. The extreme variation on apparent efficiency of absorption may have an effect on the success of PIT. Lambs should consume at least 30 g of IgG in the first 24 h of life to ensure adequate PIT.

The aim of this study was to evaluate hCG treatment on ovarian response and on pregnancy rate using a 9-day oestrus synchronization protocol in Santa Ines ewes. On a random oestrus cycle day, ewes received an intravaginal progesterone device (Primer-PR^®, Tecnopec, Brazil). Nine days later (Day 9), 30µg of d-cloprostenol (Prolise^®, Syntex, Argentina) and 250IU of eCG (Folligon^®, Intervet, Brazil) were administered and the progesterone device was removed. This moment, the ewes were randomly assigned on two groups: Control Group and hCG Group. In the hCG Group, the ewes received 500IU of hCG (Vetecor^®, Hertape-Calier, Spain) 24h after device removal. In the Control Group, the ewes did not receive any ovulation inductor. Control and hCG Groups ewes were inseminated 60h and 48h after device removal, respectively. There was no difference between the groups regarding the first ovulatory follicle diameter and the second ovulatory follicle. hCG Group ewes had shorter interval between device removal and ovulation (Control: 79.9±15.4h and hCG: 54.7±4.9h; P=0.001) and more synchronized ovulations. However, the treatment with hCG decreased the pregnancy rate after TAI (P=0,009). In conclusion, hCG administration improves ovulatory synchronisation, but causes a decrease in the pregnancy rate.