Effect of the length of the suckling period and dietary energy intake in lactation on the duration of postpartum anestrus in Creole goats

Abstract

The objective of this study was to determine the effect of the length of the suckling period and the dietary energy level on the duration of postpartum anestrus in Creole goats. Twenty-eight multiparous pregnant goats (bodyweight BW 39.9 ± 6.4 kg; mean ± SEM) each bearing a single fetus were used in a 2 suckling period (30 vs. 60 d) × 2 levels of energy intake (low (L) vs. high (H)) factorial design. Kids were separated from their dams 3 d after birth and then suckled twice per day until weaned at 30 or 60 d postpartum. Dams weaned at 30 d postpartum were hand milked for the next 30 d. Goats were individually fed chopped alfalfa hay + balanced concentrates (45:55 DM basis) at 3% of BW in the last month of pregnancy and at the same level to the L goats in the postpartum period when the H goats were fed at 4% of BW. Energy balance was estimated by difference between energy intake and calculated energy requirements. Duration of postpartum anestrus was estimated by determining the occurrence of ovulation from changes in blood progesterone concentrations. There were no significant lengths of suckling x energy intake level interactions. Goats on all treatments lost weight until 45 d postpartum with more weight loss on the low than the high energy intake level (L 4.06 ± 0.43 vs. H 1.99 ± 0.64 kg; P < 0.05). The daily 4% FCM production was similar for all treatments (overall mean 1.10 ± 0.01 kg). The difference between the postpartum anestrus period between low (129 d) and high (128 d) dietary energy levels was not significant but no goat ovulated while in negative energy balance. The effect of suckling on the resumption of ovarian activity was highly significant (P < 0.001) with goats weaned 30 d postpartum resuming ovulation 102 d after parturition compared to 155 d for those weaned 60 d postpartum. This study illustrates the importance of the bond between the doe and its kid in the prolongation of the anestrus period in goats.