Foraging behaviour, digestion and growth performance of sheep grazing on dried vetch pasture cropped under conservation agriculture

Abstract

This study aimed to investigate the replacement value of half time grazing of wheat stubbles by vetch, which had been cropped under the context of conservation agriculture (CA). Three grazing treatments were evaluated on Barbarine lambs (initial BW 18 ± 1.42 kg). Treatment 1 consists of 6‐hr grazing on dried vetch only (V). For treatment 2, the sheep were grazing 3 hr on wheat stubbles in morning and 3 hr on dried vetch in the afternoon (VWS). Treatment 3 consists of 6‐hr grazing of wheat stubbles only (WS). At grain maturity stage, biomass yield of vetch averaged 7 tons DM/ha allowing a grazing period of 2 consecutive months. Along this period, vetch conserved its pods indehiscent. Biomass and nutritive value of vetch and wheat stubbles were decreasing from the start to the end of the grazing period. Residual biomass was higher in vetch and wheat stubble assigned to treatment VWS. WS lambs spent more time on walking and standing, while V and VWS lambs allocated more time on biomass uptake. The DM, OM and CP intakes were higher in animal grazing vetch alone or combined to wheat stubble. Rumen fermentation parameters (pH, ammonia nitrogen concentration and protozoa count) were not affected (p > .05) by any of the three treatments. The average daily gain of lambs on V and VWS lambs was three times greater (p < .05) than that of WS lambs (164, 152 and 49.5 g respectively). Cold carcass yield averaged 444, 428 and 388 g/ kg for lambs assigned to V, VWS and WS treatments respectively. It is concluded that grazing vetch alone or combined with WS increased substantially the growth performance and carcass yield of lambs compared with WS grazing only. Therefore, dried vetch grazing could be a solution to make possible mulching and biomass uptake by sheep under the context of CA.

Conservation agriculture has no significant impact on sheep digestive parasitism

“…The environmental benefits of CONS A, especially regarding climate change and land preservation, are very high, and governments should encourage this type of agriculture to maintain the sustainability of agricultural activity and reduce its negative impact on the environment ( 6 , 26 , 27 ). As part of combining crops with livestock, particularly in semiarid areas, CONS A and sheep farming can be harmoniously associated ( 10 , 28 ).…”

“…Moreover, the mean carcass yield of the CONS A lamb group (445 g/kg) was slightly lower than the normal yield values for fattening lambs (between 450 and 600 g/kg of body weight) ( 23 ). This variation was probably due to genetic traits, gender, age, birth weight, and feeding level ( 28 ). There was no statistically significant difference in the mean carcass yield between the two animal batches (CONS A and CONV A lamb batches).…”