No abstract

Plant extracts have been proposed as substitutes for chemical feed additives due to their potential as rumen fermentation modifiers and because of their antimicrobial and antioxidant activities, possibly reducing methane emissions. This study aimed to evaluate the use of oregano (OR), green tea extracts (GT), and their association as feed additives on the performance and methane emissions from dairy between 28 and 87 d of lactation. Thirty-two lactating dairy cows, blocked into 2 genetic groups: 16 Holstein cows and 16 crossbred Holstein-Gir, with 522.6 ± 58.3 kg of body weight, 57.2 ± 20.9 d in lactation, producing 27.5 ± 5.0 kg/cow of milk and with 3.1 ± 1.8 lactations were evaluated (means ± standard error of the means). Cows were allocated into 4 treatments: control (CON), without plant extracts in the diet; oregano extract (OR), with the addition of 0.056% of oregano extract in the dry matter (DM) of the diet; green tea (GT), with the addition of 0.028% of green tea extract in the DM of the diet; and mixture, with the addition of 0.056% oregano extract and 0.028% green tea extract in the DM of the diet. The forage-to-concentrate ratio was 60:40. Forage was composed of corn silage (94%) and Tifton hay (6%); concentrate was based on ground corn and soybean meal. Plant extracts were supplied as powder, which was previously added and homogenized into 1 kg of concentrate in natural matter, top-dressed onto the total mixed diet. No treatment by day interaction was observed for any of the evaluated variables, but some block by treatment interactions were significant. In Holstein cows, the mixture treatment decreased gross energy and tended to decrease the total-tract apparent digestibility coefficient for crude protein and total digestible nutrients when compared with OR. During the gas measurement period, GT and OR increased the digestible fraction of the ingested DM and decreased CH expressed in grams per kilogram of digestible DMI compared with CON. The use of extracts did not change rumen pH, total volatile fatty acid concentration, milk yield, or most milk traits. Compared with CON, oregano addition decreased fat concentration in milk. The use of plant extracts altered some milk fatty acids but did not change milk fatty acids grouped according to chain length (short or long), saturation (unsaturated or saturated), total conjugated linoleic acids, and n-3 and n-6 contents. Green tea and oregano fed separately reduced gas emission in cows during the first third of lactation and have potential to be used as feed additives for dairy cows.

In the tropics, milk production systems present high diversity and distinct ability to adapt to the demands of consumers and market conditions. Knowledge of the factors that affect the quality of milk and agglomerate of production systems into fewer groups can facilitate analysis and the decisions needed to improve them. The objective of this paper was to characterize, classify and analyze dairy production systems in the Brazilian southern region, and relate their productive aspects to the physical-chemical attributes of the milk produced. A multivariate analysis was conducted with 26 indicators obtained from a survey covering 328 dairy farms. Variance was fully explained by the first three principal factors. The first factor included feeding strategies, the second included the farm's structure traits and the third included milk composition. Canonical analysis revealed distribution of farmers into three clusters. All feeding strategies, except salt supplementation, as well as monthly milk production, herd size, number of lactating cows in farm and unstable milk frequency were important discriminant variables to determinate cluster formation. The clusters were differentiated by feeding strategies used and the high standard deviation in some of these strategies demonstrated the adoption of specific strategies in different seasons. Cluster 3 had the largest monthly milk production and larger number of lactating cows, but the productivity of cows in the different clusters was not significantly different. The lower unstable milk frequency in cluster 3 is associated with more intensive use of silage, mineral-vitamin premix and commercial concentrate in the diet of animals. The physical-chemical composition of milk and the somatic cell count did not differ between clusters.

 RESUMOO objetivo do presente estudo foi caracterizar as propriedades leiteiras da região do Vale do Braço do Norte, sul de Santa Catarina, Brasil, quanto à qualidade do leite e ao perfil em infraestrutura, manejo e alimentação dos animais. Foram coletadas informações de 50 propriedades leiteiras, obtidas por meio da aplicação de um questionário estruturado, abrangendo questões socioeconômicas dos produtores, manejo do rebanho, estrutura da propriedade, caracterização dos animais, alimentação das vacas além de manejo e higiene da ordenha. As amostras de leite foram submetidas a análises de composição, contagem bacteriana total, contagem de células somáticas e estabilidade do leite ao teste do álcool. Os dados foram analisados pela análise fatorial, discriminante, canônica, e de agrupamento. As propriedades têm como principal característica a agricultura familiar, com área média de 30 hectares; destes, 15,1 são destinados à pecuária leiteira, com média de 23,1 vacas ordenhadas. Na análise fatorial, o primeiro fator representa as relações entre as práticas de higiene na ordenha e de controle/prevenção de mastite, o segundo fator compreende a infraestrutura da fazenda com o nível de produção e o terceiro fator demonstra a relação entre a suplementação concentrada, a produção e a estabilidade do leite ao teste do álcool. A análise de agrupamento formou três grupos, sendo dois compostos por produtores com maior nível tecnológico e outro constituído por pequenos produtores com menor infraestrutura e nível de tecnologia. As propriedades que apresentam infraestrutura mais adequada para a produção, maior adoção das práticas recomendadas de manejo de ordenha e critérios de alimentação mais adequados produzem leite com melhor qualidade.Palavras-chaves: contagem de células somáticas, contagem bacteriana total, composição do leite, estabilidade do leite ao álcool, manejo de ordenha ABSTRACT

Data from five experiments with dairy cows where feed was restricted to 0, 40, and 50% of the ad libitum amount, with 259 observations, were subjected to multivariate analyses to determine the effects of severity and duration of feed restriction on production, physical-chemical characteristics, ethanol stability, and somatic cell score of milk. A negative relationship was seen between the severity and duration of feed restriction with milk production, lactose content, titratable acidity, and milk stability to the ethanol test. The milk stability to the ethanol test, protein content, milk yield, and somatic cells score were the most important attributes retained by the discriminant analysis. Milk stability to the ethanol test, live weight, days in restriction, and pH were the most important characteristics explaining the variance within the different levels of feed restriction. Milk production and ethanol stability were significantly lower in both levels of feed restriction compared with the group fed ad libitum. When feed restriction was followed by refeeding, the difference observed in ethanol stability was the first discriminant variable, followed by the difference in unstable milk frequency and titratable acidity. Increments in the severity and duration of feed restriction negatively affect milk production and milk ethanol stability.