The effects of nutrition and parity on the development and productivity of Angora goats: 1. Manipulation of mid pregnancy nutrition on energy intake and maintenance requirement, kid birth weight, kid survival, doe live weight and mohair production

Abstract

Farmers report low Angora kid birth weight associated with high kid mortality. As breeding goats are likely to face energy restrictions during winter when pregnant this study investigated the effects of energy intake during mid pregnancy on Angora kidding losses, birth weight, placenta weight and productivity of does. The design was three levels of mid pregnancy nutrition (MPN) with live weight (mean±sd, 34.6±3.1kg) and parity blocks. Following artificial insemination and pregnancy scanning 102 does, including 24 twin bearing does, were fed pelleted rations in individual pens in an outdoor feedlot from day 47 of pregnancy until kidding. MPN treatments were: Control, live weight loses of 2.5kg; Maintenance, maintenance of live weight; Supplemented, moderate live weight gains. From days 105 of pregnancy until 4days postpartum the feeding was ad libitum. Feed and energy intake, live weight, body condition score and mohair production were measured. The pattern of live weight change followed the ME intake pattern. ME intake of Control does declined to 0.5–0.6 maintenance and they lost 67g/d. Supplemented does intake increased to near 2× maintenance and gained 102g/d. The maintenance ME requirement of does in mid pregnancy was determined as 384±19.7kJ/kg0.75/d. Following removal of energy restrictions, from day 117 to kidding Control does consumed more ME than Maintenance and Supplemented treatments. During the last 4 weeks of pregnancy ME intake for all treatments increased from 2× maintenance to at least 2.5× maintenance. In the last trimester does were able to substantially but not fully compensate for live weight losses or penalties induced as a consequence of energy restrictions during the middle trimester. Does gained body condition in mid or late pregnancy provided energy provision was sufficient and close to ad libitum feeding. Control does had 15% greater foetal losses prior to kidding compared with other treatments. Kid losses at birth and in the first 24h did not differ between treatments. As a consequence of compensatory gain in late pregnancy there was no significant difference in kid birth weight between treatments. MPN did not affect placenta weight although placenta weight was positively associated with kid birth weight. However, heavier does in late pregnancy produced heavier kids once allowance was made for differences in birth parity and kid sex. There were small significant effects of MPN on mohair production and diameter. The findings indicate that Angora producers should minimise doe live weight loss during mid pregnancy to avoid foetal losses, feed does well during the last trimester to optimize doe live weight and kid birth weight and provide the best care possible during kidding to optimize kid survival.