Effects of multinutrient blocks and polyethylene glycol 4000 supplies on intake and digestion by sheep fed Acacia cyanophylla Lindl. foliage-based diets

Abstract

The effect of multinutrient block supply and polyethylene glycol 4000 (PEG) on intake, digestion and rumen fermentation was studied in sheep fed with air-dried Acacia cyanophylla foliage (acacia)-based diet. In Experiment I, six Noire de Thibar breed sheep (BW = 46 kg) were used in double 3 x 3 Latin square design. All diets included about 360 g of dry matter (DM) of oat-vetch hay and acacia ad libitum. Diet D0 was without a block supplement. Diet D1 included a urea-molasses-mineral block (B1). While D2 included another type of block (B2) that differed from B1 essentially by adding polyethylene glycol 4000. Each experimental period lasted 33 days (21 days for adaptation and two periods of 5 days for measurement separated by 2 days for rest). Feed intake, apparent digestibility of organic matter (OM), crude protein (CP) and crude fibre (CF) and retained nitrogen (Nr) were measured by total faecal collection. In Experiment II, four Noire de Thibar sheep (BW = 53 kg) fitted with rumen cannulae were fed sequentially D0, Dl and D2, respectively, to 90% of intake levels as measured in Experiment I on metabolic weight (MW) base. Fermentation parameters in rumen liquid (pH, NH 3 -N, volatile fatty acid (VFA)) were measured at 0, 2, 5, 8, 10, 13, 16 and 21 h after the morning meal. Protozoal number and composition in rumen fluid were determined at 2 h sampling time. Solid digesta kinetics through the rumen was measured using chromium (Cr) mordanced acacia. The DM and CP degradation of acacia was determined using the nylon bag technique.Acacia had a relatively high content of condensed tannins (41 g kg -1 of DM) and acid detergent lignin (176 g kg -1of DM). B1 and B2 were high in CP (381 and 369 g kg -1 of DM, respectively) compared to acacia (127 g kg -1 of DM, 20% bound to fibre) and hay (75 g kg -1 of DM). The two kinds of blocks improved similarly (P < 0.001) acacia DM intake by 195 g. Block 1 increased (P < 0.001) only diet CP digestibility and Nr. Block 2 increased (P < 0.05) by a low extent DM and OM digestibility compared to D1, and remarkably (P < 0.001) CP digestibility and Nr compared to D0 and Dl. Block supplies considerably increased water intake. Both B1 and B2 increased (P < 0.001) NH 3 -N and VFA concentrations in the rumen liquid with a positive specific effect of B2 (PEG). VFA molar proportion was significantly modified by B1 and B2. B1 and B2 decreased acetate proportion and increased propionate and butyrate proportions as compared to D0 (P < 0.001). Protozoal number in rumen fluid was increased significantly by B1 and B2 (P < 0.001). PEG-containing block (B2) increased protozoal number as compared to B1. Both B1 and B2 increased (P < 0.001) solid outflow rate, with a specific increasing effect of B2 (D2) when compared to B1 (D1). Blocks supply did not modify in situ DM degradability of acacia, but B2 improved (P < 0.05) effective degradability of CP when compared to D0 and Dl which were similar. It is concluded that both B1 and B2 improved the nutritive value of acacia-based diet. A further pos...

Utilization of wheat bran and dried Acacia saligna (Labill) H.L.Wendl leaves by highland rams

“…The OM content found in this study is comparable with other authors (Ahmed, 2007;Moujahed et al, 2000;Mousa, 2011;Shumuye and Yayneshet, 2011). The CP content of A. saligna was comparable to 13.8, 13.76 and 15.7% CP (Krebs et al, 2007b;Safinaz et al, 2010;Chentli et al, 2014) and higher than the value reported by others (Shumuye and Yayneshet, 2011;Moujahed et al, 2000;Ahmed, 2007;Mousa, 2011). This variation arises from age and species of the Acacia plant, soil fertility where the Acacia plant grown and the season of the leaf harvest.…”

“…A. saligna is one of the introduced browse shrub or tree species, which is widely grown and evergreen in different agro-ecological zones of Tigray (Shumuye and Yayneshet, 2011). A. saligna has reasonably large amount of crude protein (Moujahed et al, 2000), which has the potential to supplement the predominantly poor quality fibrous feeds widely used by smallholder farmers.…”

“…The low protein digestibility of A. cyanophylla in sheep was due to the high level of condensed tannins (CT) in its foliage (Degen et al, 1995). Although the use of polyethylene glycol (PEG) to deactivate tannin has been recommended (Ben Salem et al, 1997;Moujahed et al, 2000;Ben Salem et al, 2005b;Olivares et al, 2013;Rojas et al, 2015a;Rojas et al, 2015b), its wider use under smallholder *Corresponding author. E-mail: gebreg192@yahoo.com.…”

The influence of the grape pomace on the ruminal parameters of sheep

“…Moreover, in in vivo studies (Baumgärtel et al, 2007;Famuyiwa and Ough, 1990), it was suggested that the negative effect of lignin (in grape pomace) on OMD and NDFD is more than the influence of tannins. Compared to other tanniniferous feed such as acacia when fed to sheep, the content of condensed tannins may have been relevant for nutrient digestion (Ben Salem et al, 1999;Moujahed et al, 2000). They, also, reported that multiple phenolic hydroxyl groups in tannins lead to formation of complexes mainly with proteins and, to a lesser extent, with polysaccharides, limiting their availability to animals.…”

Comparative nutritional studies of sheep and goats fed cultivated tree legumes mixture under desert condition

“…Acacia (Acacia saligna) is a leguminous shrub which provides large amounts of fodder for ruminants in marginal regions [4,5]. A. saligna has reasonably large amount of crude protein [6], high concentration of tannins [7,8]. These compounds have adverse effect on the nutritional value to the browse species and also affect feed intake and digestibility [9].…”