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Abstract
Cereal stubble and straw are widely used as animal feeds for sheep in arid areas of Morocco. Their low protein concentration limit their intake and therefore their potential of production. A 10-wk wheat (Triticum aestivum L.) stubble grazing trial was conducted to study the effects of supplementation with browse (Atriplex nummularia Lindl., Acacia cyanophylla Lindl.) foliage or medic (Medicago sp.) pods on stubble intake and sheep live weight changes. All supplements caused a positive live weight gain. However, a trend towards higher weight gain was observed for animals receiving Atriplex foliage.
A 15-wk feeding trial was then conducted to investigate the effect of the same supplements on wheat straw intake and ewe lamb live weight. Atriplex and Acacia foliage supplementation resulted in the highest and lowest straw intake increase, respectively. A metabolism study conducted at the same time to evaluate the influence of these supplements on N utilization by sheep fed wheat straw revealed that digestible dry matter intake and daily N balance were highest for the Atriplex-supplemented wheat straw diet. The diet including medic pods was ranked second and the one with Acacia was last due to some unpalatability factors. An in situ degradability study indicated that the rate constant and extent of CP degradation were highest for Atriplex foliage, closely followed by medic pods. Acacia foliage was ranked last. These findings would explain why animals receiving Atriplex foliage in addition to wheat straw (feeding trial) were the only ones to maintain weight over a 15-wk period. Medic pod supplementation resulted in an insignificant weight loss.
These results showed that foliage from palatable shrubs and medic pods can be effective protein supplements for livestock consuming wheat straw. Implementing such strategies would require that farmers plant oldman saltbush (Atriplex nummularia Lindl.) shrubs on their private land and manage medic pasture to produce enough pods to be grazed in summer.
