Inclusion of Yeast Cultures (<i>Saccharomyces cerevisiae</i>) to Dairy Cows’ Urea-Treated Rice Straw Diets Improves Mozzarella Cheese Processing and Yield

This research paper addresses the hypothesis that adding yeast cultures (Saccharomyces cerevisiae) to urea-treated cereal crop residues could improve milk composition to the level of milk produced on pastures for the manufacture of Mozzarella cheese. In three equal groups, Nine Friesian cows were randomly assigned to three treatment diets in a completely randomized design. The treatments were pasture (P), urea treated rice straw (UTRS), and urea treated rice straw with yeast inclusion (UTRS + Y). Urea inclusion was at 3.8% of the dry matter to treat rice straw, while yeast culture inclusion was 10 g/cow/day. The experimental period was 21 days, with 14 days of adaptation. Data analysis used general linear model procedure of SAS, fitting diet as a fixed effect and milk composition, syneresis, curd firmness and cheese yield as the response variables. Milk produced on UTRS diet yielded (p < 0.05) the highest fat content (4.79%) and the lowest density (1016.37 Kg·m-3) and casein-to-fat ratio (0.51). Yeast inclusion in the diet (UTRS + Y) significantly improved milk density (1022.68 Kg·m-3) with marginal reduction in milk fat content (4.53%). In cheese making, milk produced on URTS diets had significantly lower renneting time (1.4 minutes vs 3.47 minutes and 2.39 minutes), least viscous gel, lowest syneresis (755 mL vs 860 mL and 836 mL from 1000 mL), and lowest cheese yield (9.0% vs 11% and 10.5%) compared to P and UTRS + Y diets. Milk produced from P and UTRS + Y did not show any significant difference in cheese yield. The findings indicated that urea treated rice straw with yeast cultures improves syneresis, gel viscosity and Mozzarella cheese yield. Therefore, we recommend the inclusion of yeast to urea treated cereal crop residues to produce milk destined for Mozzarella cheese making.

Assessing Animal Disease Prevalence and Mortality in Smallholder Dairy Farms under Contrasting Management Practices and Stressful Environments in Tanzania

In dairy farming, deploying effective animal husbandry practices minimise disease infections and animal mortality. This improves animal health and welfare status, which is important in tropical smallholder dairy farming, where animals are persistently exposed to multiple environmental stresses. The hypothesis of this study was that animals managed in positive deviants and typical farms suffer different levels of disease infections and mortality, whether under low- or high-stress environments. The study adopted a two-factor nested design with farms contrasting in the level of animal husbandry (positive deviants and typical farms) nested within environments contrasting in the level of environmental stresses (low- and high-stress). A total of 1,999 animals were observed over 42 month period in the coastal lowlands and highlands of Tanzania. The disease prevalence was lower (p < 0.05) in positive deviant farms than in typical farms under low-stress (10.13 vs. 33.61 per 100 animal-years at risk) and high-stress (9.56 vs. 57.30 per 100 animal-years at risk). Cumulative disease incidence rate was also lower (p < 0.05) in positive deviant farms than in typical farms under low-stress (2.74% vs. 8.44%) and high-stress (2.58% vs. 14.34%). The probability of death for a disease infected dairy cattle was relatively lower in positive deviant farms compared to typical farms under low-stress (0.57% vs. 8.33%) and high-stress (0.60% vs. 6.99%). Per 100 animal-years at risk, the mortality density of cattle was lower (p < 0.05) in positive deviant farms compared to typical farms, 15.10 lower in low-stress and 2.60 lower in high-stress. These results show that compared to typical farms, positive deviant farms consistently attained (p < 0.05) lower animal disease infections and subsequent deaths, regardless of the level of environmental stress that the animals were exposed to. This implies that positive deviant farms deployed animal husbandry practices that more effectively minimised animal disease infections and deaths and therefore could maintain their animals in better health and welfare status.