RESUMO O presente trabalho teve como objetivo avaliar a produção animal em pastagem de aveia (Avena

The aim of the present study was to monitor cow milk quality and composition in two farms in the Noroeste Rio-grandense mesoregion, located in the municipalities of Palmeira das Missões and Pinhal - RS. Both herds were mixed, with animals of the Holstein (70%) and Jersey (30%) breeds. The following overall parameters were evaluated: body condition score (BCS), udder dirtiness, and calving order, and the following milk composition factors were measured: total dry extract (TDE), defatted dry extract (DDE), milk lactose, fat, and protein contents, casein, milk urea nitrogen (MUN), and somatic cell count (SCC). Multivariate statistical analysis was performed, and four factors were identified representing combinations of the measured variables. The first factor comprised negative relationships between milk production and cow breed, milk fat content, and milk protein content. The second factor comprised the positive relationships between lactation days and body condition score and milk protein content. The third factor represented the negative relationships between milk lactose content and SCC score, calving order, and BCS. The fourth factor was composed of the positive relationship between delivery order and udder dirtiness. Cluster analysis revealed that individual cows could be categorized into three groups. Monitoring the breed, calving order, body condition score, lactation days, milk production, fat, protein, and lactose contents, somatic cell counts, and udder dirtiness in cows allows greater control of the herd, allowing potential shortcomings to be rectified quickly and economic losses to production to be minimized.

This longitudinal retrospective study evaluated production and composition of milk from dairy cows according to season on a rural property in Palmeira das Missões, Rio Grande do Sul, Brazil, between January 2009 and December 2016. Milk yield per hectare per month was the primary variable measured, along with chemical composition (total dry extract, defatted dry extract, fat, protein, and lactose), somatic cell count, and total bacterial count of milk. Production in summer (513.53 kg/ha/month) did not differ (p > 0.05) from that in fall (504.69 kg/ha/month) or spring (564.63 kg/ha/month), but production in winter (639.20 kg/ha/month) was significantly higher than in summer (p < 0.0057). The real price of milk did not differ (p > 0.05) among seasons. The total dry extract content differed (p < 0.0059) between seasons. However, the cooler fall and winter seasons favored the production of total solids. The defatted dry extract content was higher (p < 0.0001) in winter (8.65%), compared to the other seasons of the year. Fat content did not differ (p > 0.05) among seasons. Protein content differed (p < 0.0200) between summer (3.01%) and winter (3.16%), but both seasons did not differ (p > 0.05) from fall (3.13%) or spring (3.05%). Winter lactose levels (4.52%) were higher (p < 0.0011) than during other seasons. The somatic cell count did not differ (p > 0.05) among seasons, demonstrating that the evaluated herd possesses standard mammary gland health. The total bacterial count did not differ (p > 0.05) among the seasons, demonstrating that the hygiene of the facilities remains constant. As expected, the temperature and humidity index varied (p < 0.0001) with the seasons, and the deleterious effects were more pronounced in summer and spring, as they are the hottest seasons in humid subtropical environments. The results emphasize that the organized management of milk production reduces the variation in milk composition, making it easier to maintain a consistent high milk quality and also generating extra revenue.