No abstract

Summary Bud‐sprouting dynamics, sprouting base temperature and reserve mobilization of rhizomes and stolons of Cynodon dactylon (L.) Pers. were characterized in a laboratory experiment under dark conditions. In addition, the dynamics of sprout emergence were determined during 2 years under field conditions. In the laboratory experiment, buds from the vegetative structures did not sprout at temperatures below 7^C. The rate of sprouting increased with temperature within the range 11–33^C, and a base temperature of 7.71^C was determined for bud sprouting of rhizome and stolons of the weed. An exponential model is proposed relating the percentage of sprout emergence in the field to accumulated thermal units, calculated as the sum of the daily mean air temperature above the base temperature of bud sprouting. This model satisfactorily predicted the dynamics of C. dactylon sprout emergence in sunflower (Helianthus annuus L.) crop fields. The efficiency of carbohydrate reserve use during sprout growth was highly dependent on temperature and type of vegetative structure The efficiency was maximum at 20^C and was higher for rhizomes than for stolons. The main factors influencing bud sprouting and early weed establishment are discussed.

The use of brown rice grain as corn grain replacer in dairy cow diets was investigated. The following treatments were evaluated: zero, 33, 63, and 100%. The experimental diets were iso in protein, energy and fiber levels. Eight multiparus Jersey cows were used. A replicated Latin square experimental design was applied. The inclusion of brown rice had no effect (P > 0.05) on dry mater intake and their constituents, apparent digestibility, production and milk composition, feed efficiency and blood chemistry profile. Therefore, the brown rice grain can be used replacing corn grains alternative feedstuff in dairy cow diets.

Resumo -O objetivo deste trabalho foi avaliar o efeito da interação entre sistemas produtivos e estações do ano sobre a qualidade química e microbiológica do leite bovino, além de propor um índice de potencial nutracêutico do perfil de ácidos graxos do leite. Três propriedades foram avaliadas mensalmente, durante as diferentes estações do ano, em quatro graus de especialização dos sistemas de produção: altamente especializado, especializado, semiespecializado e não especializado. Os sistemas de produção e as estações do ano interferem de forma conjunta no perfil de ácidos graxos e, de forma isolada, na qualidade química e microbiológica do leite. As maiores contagens de células somáticas e os menores conteúdos de proteína foram observados no verão, e o grau de especialização das unidades produtivas esteve indiretamente relacionado à contagem bacteriana total no leite. No inverno, sistemas não especializados produziram leite com o melhor índice nutracêutico, que apresentaram os maiores teores de ácidos graxos poli-insaturados, ácido rumênico (CLA, 18:2n7-c9,t11) e ácido t10,c12-octadecadienoico (CLA, 18:2n6-t10,c12).Termos para indexação: ácido linoleico conjugado, alimentos funcionais, perfil de ácidos graxos, qualidade do leite bovino. Quality and nutraceutical potential of bovine milk in different production systems and seasonsAbstract -The objective of this work was to evaluate the effect of the interaction between production systems and seasons on the chemical and microbiological qualities of bovine milk, besides proposing a potential nutraceutical index of milk fatty acid profiles. Three farms were assessed monthly, along the different seasons, for four specialization levels of the production systems: highly specialized, specialized, partially specialized, and nonspecialized. The production systems and the seasons jointly interfere in fatty acid profiles, and singly interfere in the chemical and microbiological quality of milk. The highest somatic cell counts and the lowest protein contents were observed in the summer, and the specialization level of the production units had an inverse relationship with the total bacterial count. During winter, nonspecialized systems produced milk with the best nutraceutical index, with the highest contents of polyunsaturated fatty acids, rumenic acid (CLA, 18:2n7-c9,t11) and t10,c12-octadecadienoic acid (CLA,c12).

The aim was to evaluate how the fodder pre-dehydration time and its phenological stages influence on ruminal degradability and digestibility of ryegrass silage. The evaluated samples consisted of treatments: Vegetative: Cut and ensiled; cut + 4 hours pre-drying and ensiled and; cut + 7 hours pre-drying and ensiled; Pre-flowering: Silage cutting and ensiled and 4 hours pre-drying and ensiled; Flowering: cut and ensiled, no pre-drying, with four replications each treatment. Silage was storage for four months. It was carried out three in situ digestibility assays to determine the curve of ruminal degradability at different times (3, 6, 9, 12, 24, 48 and 72 hours), like in situ digestibility and other three assays of 24 hours and 48 hours to determinate in vitro digestibility of silage. The digestibility of ryegrass silage was influenced by both the pre-dehydration times and phenological stage, and the dehydration time of cut and silage had a high proportion of degradable components, with higher degradation rate by 24 hours of incubation. The in vitro digestibility of the ryegrass silage was greater than that in situ for up to 48 hours. The digestibility of the ensiled ryegrass biomass was influenced by the dehydration times, as well as the plant growth stage, regardless of the methodology used, being higher values for the treatment without previous drying of the vegetative stage.