Protein supplementation for sheep fed with tropical forage

Abstract

The effects of increasing levels of protein supplementation (50, 100, 150 and 200 animal per day) and mineral salt on feed intake, nutrient digestibility and ingestive behavior of sheep consuming tropical forage (Pennisetum purpureum Schum) were evaluated. Five non-castrated crossbred lambs (½ Santa Inês x ½ undefined breed) with average initial body weight of 35.0 kg (± 4.40 kg) were allocated in individual cages and analyzed in a 5x5 Latin square experimental design composed of five animals, five treatments and five evaluation periods of 14 days each. The contrast (protein supplement vs. mineral mixture) was not significant (p>0.05) for total dry matter intake, total organic matter intake, total ether extract intake and total carbohydrate intake variables. However, it was significant (p<0.05) for the variables forage dry matter intake, total crude protein intake, total mineral matter intake, total neutral detergent fiber intake and total non-fibrous carbohydrate intake, demonstrating possible replacement of forage by the supplement. Although the diet dry matter digestibility declined linearly (p <0.05), there was a significant linear increase effect of supplementation (P <0.05) on apparent digestibility of neutral detergent fiber, non-fibrous carbohydrates and consumption of digestible non-fibrous carbohydrates. This was due to higher participation of supplement in the diet ingested by supplemented sheep. The type of supplementation (protein or mineral mixture) did not affect the animals€™ daily activities. Protein supplementation did not affect the water ingestion (P <0.05), demonstrating that even at the highest level of supplementation (200 g/day), animals were not induced to drink more water by the diet. We conclude that increasing levels of protein supplementation associated with good quality elephant grass resulted in increases in sheep digestive parameters, and supplementation below 100 g day-1 resulted in similar parameters to those of sheep receiving mineral mix (control). Additionally, protein supplementation did not affect (P> 0.05) either the water intake or ingestive behavior of sheep, with rumination and rest coinciding with dusk and dawn.