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Two experiments were carried out to evaluate the effect of partial replacement of concentrate with 2 types of feed blocks (FB) on rumen protozoa numbers, nutrient utilization, microbial N flow to the duodenum, and milk yield and composition in goats. The concentrate included oat, corn grain, barley, soybean meal, salt, and vitamin-mineral mixture. The FB (types I and II) were composed of crude 2-stage olive cake (120 or 100g/kg), fava beans (0 or 400g/kg), barley (320 or 200g/kg), beet molasses (220 or 100g/kg), sunflower meal (180 or 0g/kg), quicklime (70 or 90g/kg), salt (60g/kg), urea (0 or 20g/kg), and vitamin-mineral mixture (30g/kg). In experiment 1, 6 adult, dry, nonpregnant, rumen-fistulated Granadina goats (46.9+/-2.15kg of BW) were used and 3 trials were carried out. In each trial, 2 goats were randomly assigned to receive 600g of alfalfa hay and 400g of concentrate (diet AC), 600g of alfalfa hay, 200g of concentrate, and FB I (diet ACBI), or 600g of alfalfa hay, 200g of concentrate, and FB II (diet ACBII) with 6 replications per diet. The FB were supplied ad libitum. The ratio of purine bases to N was higher in solid- and liquid-associated bacteria for FB goats than for AC goats. In experiment 2, 18 Granadina goats (39.6+/-1.89kg of BW) in the middle of the third lactation were used, and 3 trials were carried out by following a 3 x 3 Latin square experimental design. In every trial, 6 animals randomly received 1.0kg of alfalfa hay supplemented with 1.0kg of concentrate (diet AC) or 0.5kg of concentrate and FB I and II (diets ACBI and ACBII) with 18 replications per diet. The FB were supplied ad libitum. The intakes of organic matter and fat were higher with the AC diet than with the FB diets. The intake of acid detergent fiber was higher for FB-containing diets than for the AC diet. The neutral detergent fiber digestibility of FB diets was higher than that of the AC diet. Energy intake was higher for diets AC and ACBII than for ACBI. Microbial N flow was affected by diet. Milk yield was higher in goats fed the AC diet than in those receiving the FB diets. Conjugated linoleic acid content was higher in milk from FB than in milk from AC goats. Our study suggests that FB type II based on local ingredients could be used advantageously to reduce half of the amount of concentrate without detrimental effects on nutrient utilization, N value of the diet, and milk composition. The decrease of milk yield with ACBII compared with that obtained with the AC diet could be compensated by better quality of milk, decreased cost of feeding, and environmental advantage derived of including by-products in FB.

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1996). Effect of increasing level of spineless cactus ( Opuntia cus indica var. inermis) on intake and digestion by sheep given straw-based diets. AbstractThe effects of spineless cactus (Opuntia ficus indica var. inermis) supply on digestion of wheat straw was studied n rumen cannulated sheep. In addition to urea (10 g) and mineral and vitamin mixture (30 g), the animals •eceived wheat straw alone or supplemented with graded levels of spineless cactus (150, 300, 450 or 600 g dry natter (DM) per head per day). The diets were studied in five successive 25-day periods from February to June 992 in Tunisia. "Water consumption, food intake, digestibility, diurnal variations of ruminal fermentation (pH, mmonia nitrogen, volatile fatty acids, protozoal concentrations in rumen fluid) and cellulolytic activity in the umen were measured. Spineless cactus had high contents of ash (260 g/kg DM) and water (926 g/kg fresh weight) and low neutraldetergent fibre content (185 g NDF per kg DM). Crude protein (CP) content of spineless cactus was 2-5 times reater than that of wheat straw (58 v. 23 g/kg DM, respectively). Drinking water consumption was substantially educed (P < 0-001) as the level of spineless cactus increased. When spineless cactus supply exceeded 300 g DM per ay, sheep consumed practically no drinking water. The voluntary intake of straw increased significantly with vineless cactus level. Total diet apparent digesibilities of DM, organic matter and CP tended to increase with mneless cactus supply. Such increase was significant only with the 450 and 600 g levels of cactus. NDF and acidetergent-fibre apparent digestibilities were not affected by spineless cactus supply. Addition of spineless cactus up i 300 g DM significantly increased ruminal ammonia nitrogen (P< 0-001) but there was no additional effect with irther supplementation. When sheep were supplemented with spineless cactus, total rumen volatile fatty acid icreased and acetate : propionate ratio decreased significantly. Moreover, spineless cactus supply increased total wtozoa number and reduced significantly rumen cellulolytic activity measured as DM and NDF disappearance of heat straw from incubated nylon bags. keywords: cactaceae, intake, rumen digestion, sheep, wheat straw.