Consequences of Post-grazing Residues Control and Birth Season on the Body Traits, Reproductive Performance and Offspring’s Growth of Suckling Goats and Ewes Reared at Pasture in Guadeloupe (FWI)

Abstract

In Guadeloupe small ruminants (SR) are reared for meat production under pasture conditions. Intensive rotational grazing systems (irrigated, fertilised and high stocked) allow reasonable levels of production but generate high post-grazing residues. Experiments were designed to control them. A system in which residuals were mown (RM) was tested in comparison to the control system (Residuals Remained, RR). The same design was carried out for two years with Creole goat (G) and Martinik sheep (S). An accelerated reproductive rate (3 parturitions over 2 years) was carried out. Systems were compared at three parturition seasons per year (dry, intermediate and rainy seasons). Each group was composed of 20 goats (36.0±2.5 kg) or 20 ewes (46.8±2.4 kg). The female body traits did not vary according to pasture management and seasons. The stocking rate averaged 1,400 kg LW/ha. The mean fertility rate for does varied significantly (p<0.05) within the kidding season, from 80.4±0.5% to 93.7±2.9% while the mean litter size was 2.30±0.07 total kids born. No effect of pasture system was observed. Corresponding values for ewes were 83.2±12.8% vs. 75.6±12.5% (p<0.05) and 2.43±0.24 vs. 2.03±0.29 (p<0.01) total lambs born for SRM and SRR ewes, respectively. A seasonal effect was observed upon ewe performances. The preweaning mortality of kids and lambs averaged 16.3% and 14.4%, respectively. It was 7 and 9 percentage points more (p<0.01) for RR than for RM kids and lambs, respectively. For both species, weaning took place at an average age of 81.4±3.6 days. In Creole kids, live weight at birth and at weaning were 1.9±0.2 kg and 8.9±0.8 kg, respectively. In the Martinik sheep, the traits averaged 2.9±0.2 kg and 18.9±0.9 kg. For both traits in both species, significant (p<0.05) group×season interactions were recorded. The consequences of elimination of post-grazing residues varied according to the SR species, the environmental conditions and the animal physiological status. The forage characteristics were not limiting factors since forage availability in the RM systems (2,300 and 2,600 kg DM/ha, respectively) and chemical composition were at satisfactory levels (CP content averaged 12 and 10%). It is recommended to develop new grazing system which would allow the use of post-grazing residues instead of mowing the refusals. (Asian-Aust. J. Anim. Sci. 2003. Vol 16, No. 8 : 1108-1117)