Effects of partial replacement of concentrate with feed blocks on nutrient utilization, microbial N flow, and milk yield and composition in goats

Abstract

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.

Review and Analysis of Alternatives for the Valorisation of Agro-Industrial Olive Oil By-Products

“…A significant change is shown in the composition of goat milk with increased levels of OC in the diet. A commonly reported finding is that contents of milk fat and milk total solids, as well as milk yields, increase under an OC diet, with a reduction in saturated FAs and an increase in monounsaturated FAs compared to the control [20,30,32]. These authors agree that the addition of moderate amounts of oil by-products to the diets of dairy goats has favourable effects on milk FA composition from the point of view of the human consumer, without negative effects on animal performance.…”

“…Nasopoulou et al [18] review the evidence of olive by-products as feed for aquaculture and livestock, concluding for both that moderate consumption does not affect growth and improves the FA profile of animal products by reducing saturated acids and increasing unsaturated components both in meat and milk [19]. When ruminants are fed a diet with levels of OP below 10%, it results in a reduction in feeding costs and an improvement in milk composition without impacting milk yield [20].…”

Trends in goat research, a review

“…However, senescent leaves are only low-quality forage. In the same way, Ben Salem et al (2010) discussed the use of Atriplex nummularia to feed goat and sheep.…”

“…Molina-Alcaide et al (2010) studied the effects of partial replacement of concentrate with feed blocks on nutrient utilisation, microbial N flow, and milk yield and composition in goats, observing good results when feed blocks were used but reduced milk yield. The philosophy 'from farm to fork' can be applied to the goat sector nowadays.…”

Influence of Some Factors on In Vitro Gas Production of Different Feed Groups and Possibilities for Its Prediction

“…The inclusion of agro-industrial products in ruminant feeds could modify fatty acid profile of milk depending on the inclusion level, chemical composition and nutritional value of feeds (Leiber et al, 2005;Vasta et al, 2008;Molina-Alcaide et al, 2010). In dairy cows, lauric acid could be added to rations in order to decrease methane emissions (Külling et al, 2002).…”