W. Ventura

Effects of stocking density and supplement level on milk production and cheese characteristics in Brown cows grazing on mountain pasture.

Twenty-eight Brown cows were maintained on a mountain pasture for a period of 40 days and assigned to 4 groups following a factorial design 2 stocking density (0.7 and 1.4 cows/ha)x2 supplement levels (2.4 and 4.8 kg organic matter (OM)/d). Herbage intake, animal body condition score (BCS), milk yield, milk chemical and coagulation properties, cheese composition, rheology and sensory characteristics were measured. The average herbage intake was 12.2 kg OM/d, with a significant effect related to stocking density (low, 13.1 v. high, 11.4 kg OM/d). BCS variation was always negative and changed with supplement level, although with no statistical significance (-0.43 points on average). Milk yield was lower for the group with lower availability of herbage (low supplement and high stocking density: 15.9 kg/d), whereas it was comparable among others groups (16.9 kg/d on average). The group with high supplement and low stocking density produced milk with worse cheese making properties. Cheese composition analyses showed an effect of supplement level on calcium content, and on parameters for degree of ripening, such as nitrogen fractions and lipolysis index. As for the textural parameters, hardness and gumminess were found to be higher with the low level of supplement. The different level of supplementation could differentiate the groups on the basis of the sensory perception of cheese.

Effect of type and level of supplement on performance of dairy cows grazing on alpine pasture

Abstract An experiment was carried out on 32 dairy cows (average yield 21.9 ± 2.7 kg/d) grazing on summer alpine pasture, in order to examine the effect of two types of supplement - Starchy (42% of cereal) and Fibrous (41% of beet pulp) - both provided at two different levels - Low (1 kg of supplement per 5.0 kg of energy corrected milk (ECM)) and High (1 kg of supplement per 3.3 kg of ECM) - on herbage intake, milk yield and quality. The supplement was distributed twice a day, during milking, at a constant level throughout the experiment (July and August), as calculated according to the daily milk yield in a one-week preliminary period. Meteorological measurements, herbage quality and availability, herbage intake, animal body condition score (BCS), milk yield, chemical and rheological traits were determined. The herbage intake was higher (11.9 kg organic matter (OM)/d) with the Fibrous supplement at Low level. Even if the supplementation covered up to one third of the total intake of OM, none of the experimental groups increased BCS, and the Starchy-Low group showed a decrease in BCS significantly different from zero. The increase in the level of supplementation (from 3.5 to 5.0 kg OM/d in Low and High groups, respectively) improved the ECM yield by an average of 1.2 kg/d (P<0.05), without significant changes in the chemical composition of the milk, while the supplement type had no significant effects on either milk yield or composition. The mean coagulation properties were better with the Fibrous supplement as compared to the Starchy one – rennet clotting time (r): 16’24’’ vs 19’15’’ (P<0.05), time for aggregation (K20): 5’03’’ vs 6’45’’ (n.s.), gel firmness (a30): 26.1 mm vs 20.8 mm (P<0.05) - without significant differences derived from the level of supplementation.