Biyouna Chadli Derrida
Investigations on dairy performances and feeding controls of Holstein breed dairy cattle located in Constantine were carried out for a period of 12 months to find the quantitative and qualitative response of milk production to the livestock practices. Thus, samples of cow milk were made monthly, analyzes of physical, chemical and bacteriological composition were made. In total, 144 samples were used to build a typology of milk into 3 classes. Females produce an average of 4747 kg milk in 297 days of lactation. This result was obtained from rations where the proportion of concentrates in the total energy intake averaged 60.40%. Increase of this contribution in the diet does not lead to significant changes in the quantity of the produced milk. Beyond 12 kg of milk, cows are able to produce 34% of the expected milk. It seems that much of the concentrates was not valued in milk production. In any case, the majority of the collected milk can be described as satisfactory quality in terms of physico-chemical parameters. However, the hygienic quality was bad. No class doses combine rich milks in useful materials with low contamination and absence of antibiotic residues.
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