Effect of Polyethylene glycol 4000 supplementation on the performance of the indigenous Pedi goats fed different levels of Acacia nilotica leaf meal and Ad libitum buffalo grass hay.

Abstract

Two experiments were carried out to determine the effect of the level of Acacia nilotica leaf meal supplementation plus 23 g polyethylene glycol 4000 on diet intake, digestibility, and growth rate of indigenous Pedi goats fed ad libitum Buffalo grass, Buchloe dactyloides, hay. The first experiment lasted for 37 days, with the first 30 days being for adaptation and the last 7 days being for collection. Twenty yearling male Pedi goats weighing 22 ± 0.5 kg live weight were allocated to 4 treatments in a 2 x 2 Factorial arrangement in a Completely Randomised Design. Acacia nilotica leaf meal contained 120 g crude protein per kg DM, indicating its potential as a browse source for ruminants. It, also, contained high amounts of total phenolics (2.04 % DM) and low amounts of condensed tannins, both extracted (0.37 % DM) and unextracted (1.83 % DM). Increasing the level of Acacia nilotica leaf meal supplementation to 120 g increased (P<0.05) crude protein intake (38 g/kg DM) when compared to 80 g supplementation (34 g/kg DM). Supplementation with 23 g PEG 4000 increased (P<0.05) the crude protein intake where goats were supplemented with 120 g of A. nilotica leaf meal. However, PEG 4000 supplementation did not have an effect (P>0.05) on intake when goats were supplemented with 80 g of Acacia nilotica leaf meal. Supplementation with 120 g of Acacia nilotica leaf meal increased (P<0.05) diet digestibility of DM (0.57), OM (0.60) and CP (0.71) by the goats. Similarly, supplementation with 23 g PEG 4000 increased (P<0.05) DM (0.65), OM (0.66) and v CP digestibilities (0.76) where goats were supplemented with 120 g of A. nilotica leaf meal. Polyethylene glycol 4000 also increased (P<0.05) diet CP digestibility where goats were supplemented with 80 g of Acacia nilotica leaf meal. However, 23 g PEG 4000 did not have a significant (P>0.05) effect on diet digestibility of DM and OM where goats were supplemented with 80 g of Acacia nilotica leaf meal. In vivo NDF and ADF digestibility were not affected by the treatments. Level of Acacia nilotica leaf meal supplementation plus 23 g of PEG 4000 had a significant (P<0.05) effect on the daily live weight change of the goats. The effect was higher where goats were supplemented with 120 g of A. nilotica leaf meal when compared to 80 g supplementation. Blood urea concentrations were improved (P<0.05) by level of A. nilotica supplementation and PEG supplementation. It is concluded that PEG 4000 has the potential to improve the feeding value of Acacia nilotica leaf meal and can, therefore, be used in the feeding systems for ruminant animals. The second experiment determined the effect of A. nilotica leaf meal supplementation and PEG 4000 supplementation on in vitro diet digestibility. Level of Acacia nilotica leaf meal supplementation plus 23 g PEG supplementation improved (P<0.05) in vitro diet DM, OM and CP digestibilities where 120 g Acacia nilotica leaf meal was supplemented. Similarly, 23 g PEG 4000 supplementation also improved (P<0.05) in vitro diet CP digestibility where 80 g Acacia nilotica leaf meal was supplemented. However, level of A. nilotica supplementation plus PEG 4000 supplementation had no vi effect (P>0.05) on in vitro NDF and ADF digestibilities. In vivo diet DM, OM and CP digestibilities were positively and significantly (P<0.05) correlated with in vitro diet DM, OM and CP digestibilities. It is, therefore, concluded that in vitro diet DM, OM and CP digestibilities have good capacity to predict in vivo diet DM, OM and CP digestibilities.