F. C. Mendonça

Diurnal behavior of dairy cows on alfalfa pastures supplemented with corn silage and concentrate

Avaliou-se o comportamento ingestivo de vacas leiteiras com acesso restrito ou irrestrito a uma pastagem de alfafa suplementada com silagem de milho e concentrado. Utilizaram-se 16 vacas da raca Holandesa, em estadio medio de lactacao, em delineamento em blocos ao acaso. Os tratamentos foram: silagem de milho substituida parcialmente por pastejo restrito ou irrestrito de alfafa. As vacas foram manejadas em sistema de pastejo rotacionado e a quantidade de concentrado foi igual em ambos os tratamentos. As atividades comportamentais observadas foram pastejo, ruminacao e ocio, das oito as 19 horas, em quatro ocasioes. No pastejo irrestrito, observou-se que, nos horarios entre 14 e 17 horas, o pastejo foi intermitente e de curta duracao, enquanto no pastejo restrito a atividade de pastejo foi mais prolongada durante a manha e no final da tarde. A restricao no tempo disponivel para pastejo da alfafa influenciou marcadamente a distribuicao, no decorrer do dia, do tempo gasto em pastejo, da ruminacao e do ocio. Entretanto, nao se observou este efeito no tempo total gasto nestas atividades.

Desempenho de vacas leiteiras em pastagem de alfafa suplementada com silagem de milho e concentrado e viabilidade econômica do sistema

The effect of partial replacement of corn silage for alfafa grazing on dairy cows performance and profitability was evaluated. Twenty-four Holstein dairy cows in mid-lactation were used in a randomized block design. Treatments were: a corn silage-based diet fed on drylot, or partial replacement of corn silage for either restricted alfalfa grazing or unrestricted grazing. A rotational grazing system was used and the amount of concentrate fed was the same in all treatments. Forage availabilities were 2,338 and 1,878kg/ha of dry matter (DM) and offered at 1.8 and 4.2kg of DM/100kg of live weight under restricted and unrestricted grazing, respectively. No difference in milk production was observed among treatments, averaging 25.9, 25.8, and 25.2 liters per cow on feedlot, restricted grazing, or unrestricted grazing, respectively. Milk production per hectare was 59.3L/day on restricted grazing and 63L/day on unrestricted grazing, whereas it was 45.7L/day on drylot. Partial replacement of corn silage for alfalfa grazing did not limit animal performance and it would be economically advantageous as compared to drylot feeding.

Climatic risk zoning for corn and palisade grass (Brachiaria brizantha cv: Marandu) cultivated in integrated crop-livestock systems in São Paulo state, Brazil

Climatic risk zoning allows the identification of areas of low risk of reduced crop productivity due to climatic events. In Brazil, losses to agriculture due to climate are mainly caused by drought. The objective of this research was to determine areas of low climatic risk for corn and palisade grass cultivated in integrated crop-livestock systems in Sao Paulo state. Corn varieties characterized by a 120-day growing cycle and soil with three different water holding capacities (sandy, medium and clayey soils) were considered. A daily water balance model was used to simulate planting dates between September and December. The water requirement satisfaction index (WRSI) was calculated for critical phenological phases of both cultures (germination, emergence and tillering of palisade grass and flowering and grain filling of corn). The WRSI values, calculated for a minimum frequency of 80%, were located spatially using the SPRING v. 5.1 geographic information system and the most favorable periods for sowing in different areas were determined. The results showed that there are areas of low climatic risk for cultivation of corn and palisade grass in integrated crop-livestock production systems in Sao Paulo state. Although climatic risk in these areas also depends on soil type, the most favorable period for planting is between October and November.