Worldwide, milk analysis is an satisfactory measurement of milk quality on dairy farms. Milk composition is the base for payment systems, so knowledge of its characteristics at different periods is essential for modern dairy producer. The aim of the study was to evaluate the effects of year, season, stage of lactation, and lactation number on variations in milk yield and composition of Holstein cows (n=148,604). Milk yield estimated by multiple regression was 25,50L/cow/day. Winter was the season with the highest milk yield and the highest protein and lactose content. Milk fat was highest in the fall, in cows in late lactation and also in primiparous cows. Lactating cows from 6 to 60 days in lactation and those in 2nd or 3rd lactation showed the highest milk yield. Lactose concentration was positively correlated with milk yield. Somatic cell score was negatively correlated with milk yield and with lactose concentration. Most important variations in milk characteristics occur among seasons, lactation stages and parities. Mammary gland health is yet the greatest challenge to be overcome.

This study aimed to determine the impact of different post-partum disorders on milk yield and composition. One hundred and fifteen Holstein cows from a commercial dairy farm located in the state of Rio Grande do Sul in southern Brazil were monitored up to 62 days post-partum. During this period, body condition score evaluation and animal clinical examination were conducted. Percentages of fat, protein, and lactose, as well as somatic cells score, were determined in milk samples. The AST activity and concentrations of NEFA, calcium, and BHBA, were analyzed in blood samples. The occurrence of clinical disorders was identified in 30 (26%) cows. Subclinical disorders were identified in 64 (56%) cows. Only 21 (18%) cows did not suffer any kind of disorder within the studied period. In this study, no significant differences were found in milk production, protein, and somatic cell count in clinical, subclinical, and healthy cows. Milk fat and the fat: protein quotient (F:P) were higher in cows with clinical disorders and the 6 to 21 days in milk, and lactose were lower in cows with clinical disorders and the 22 to 42 days in milk (P<0.05).

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This study vised to detect possible changes in chemical and cellular composition of cow’s milk at different milking sessions and to test if proportional or composite milk sampling can be used instead of separate milk analysis. Two experiments were conducted: one in cows milked thrice daily and the other one in cows milked twice daily. In both experiments, three milk samples were collected from each cow in each milking session in order to determine milk composition at each milking; to have a composite sample, i.e., a single sample from the same aliquots of milk from each milking session; and to have a proportional sample, i.e., a single sample from each milking session in a volume proportional to milk volume yielded. Fat content and fat to protein ratio were higher in the afternoon on both experiments. Protein content was larger in the afternoon on cows milked twice daily, but not on cows milked thrice daily. Lactose level was not different across the milking sessions in any of the experiments. The urea level was higher in the afternoon and evening milking on cows milked thrice daily, and in the morning milking on cows milked twice daily. Somatic cell count did not differ between milking in any experiment. No difference in milk composition was noted between proportional and composite samples on cows milked thrice or twice daily. The collection of proportional and composite samples is recommended in twice or thrice daily milking sessions so that the analysis of milk components becomes more easy and cheap.

As interações que ocorrem no sistema Integração Lavoura-Pecuária (ILP) são complexas, uma vez que, além da planta e do solo, existe a participação do animal. Em alguns lugares, otimizar esses três componentes juntos é um desafio, principalmente o uso do solo, da terra e dos recursos naturais presentes. Na região sul do Brasil, durante o período de outono ao início da primavera é o período do ano de menor taxa de utilização de aproveitamento da terra. . Nesse período, existe uma ociosidade grande na utilização do solo, e com isso há a necessidade de melhor aproveitamento dessas áreas para gerar recursos para sustentabilidade do homem no campo. Com o intuito de otimizar a produção nessas áreas, busca-se a maior eficácia no plantio e cultivo de culturas de inverno, que possam ser utilizadas para produção de pré-secado, silagem e colheita de grãos com destino para o aproveitamento para alimentação animal. Diante das considerações, o referido artigo visa retomar os principais fatores que interferem diretamente na produtividade do trigo duplo-propósito submetido a diferentes doses nitrogenadas e manejos de utilização.