Dairy Cow Performance on Pasture-Based Feeding Systems and in Confinement

Interest in grazing systems is growing among farmers in the USA as a means of reducing feed costs for lactating dairy cows. An experiment was conducted near Gainesville, FL to compare milk production and composition and milk income minus feed costs from two pasture-based systems with those of a conventional confinement housing system over a 276-d period. System 1 was based on a mixture of rye (Secale cereale L.), annual ryegrass (Lolium multiflorum Lam.), crimson clover (Trifolium incarnatum L.), and red clover (Trifolium pratense L.) during the winter-spring seasons and pearl millet (Pennisetum glaucum [L.] R.Br.) during the summerfall seasons. System 2 utilized a rye-ryegrass mixture (no clover) during winter-spring and bermudagrass (Cynodon spp.) during summer-fall. Concurrently, cows managed in free-stall housing at the university farm comprised System 3. Cows in confined housing produced 20% more milk than cows on pasture, but feed cost of grazing cows was about one half that of confined cows. Milk income minus feed costs was $5.56,$5.84, and $5.34 cow-1 d-1 for Systems 1, 2, and 3, respectively

Efeito de pastagens de inverno e de verão em características físicas de solo sob plantio direto Effect of annual winter and summer pastures on soil physical characteristics, under no-tillage

Algumas características físicas de solo foram avaliadas após sete anos (1995 a 2001), num Latossolo Vermelho Distrófico, em Coxilha, RS, em seis sistemas de produção de grãos integrados com pastagens anuais de inverno e de verão e em floresta subtropical. As culturas, tanto de inverno como de verão, foram estabelecidas sob plantio direto. Mediante contrastes, foram comparados os valores das características físicas do solo em cada sistema nas camadas 0-0,05 e 0,10-0,15m. Nos sistemas I e II e na floresta, a densidade de solo e a resistência à penetração foram maiores na camada superficial em relação à camada mais profunda. No sistema II, porosidade total e microporosidade foram menores na camada superficial. O mesmo comportamento das características foi verificado na floresta subtropical para porosidade total e microporosidade. A floresta apresentou densidade de solo e resistência à penetração menores do que a maioria dos sistemas estudados em ambas as camadas, indicando que o solo, sob manejo antrópico, pode sofrer alterações nas características físicas. Os solos sob diferentes sistemas de produção, integrando lavoura e pecuária, apesar de apresentarem indícios de desestruturação, não atingiram níveis considerados críticos.<br>Soil physical characteristics were evaluated, after seven years (1995 to 2001), on a typical Dystrophic Red Latosol located in Coxilha, State of Rio Grande do Sul, Brazil. Six systems integrating crop production with livestock and a subtropical forest were evaluated. Both winter and summer crops were seeded under no-tillage. Cropping systems and soil of different sampling depths were compared using the contrast procedure. In the I and II sistems and in the forest, the soil density and the resistance to penetration increased in the top layer (0-0,05m) concerning the deeper layer (0,10-0,15m). In the II system, total porosity and microporosity decreased in the surface. In the subtropical forest, the some was observed in relation to total porosity and microporosity. The forest showed decrease on soil density and resistance to penetration, compared to most crop systems studied, from 0-0,05m layer to 0,10-0,15m layer. Soil degradation in the systems could not be considered severe

Influência de cortes similando pastejo na composição química de grãos de cereais de inverno Cut effects simulating grazing on the chemical composition of grains of winter cereals

A demanda crescente pela integração lavoura-pecuária no planalto sul-rio-grandense direciona ao aproveitamento dos cereais de inverno para duplo propósito (forragem e grão). Assim, é necessário um melhor conhecimento dessas culturas relativamente à utilização como forragem e ao valor econômico dos grãos no uso potencial para alimentação humana ou animal. O objetivo deste estudo foi avaliar a influência de cortes (um e dois), simulando pastejo bovino, na composição química dos grãos de aveia-branca (UPF 14), de aveia-preta (comum), de centeio (BR 1), de triticale (BR 4), de cevada (BR 2) e de trigo (IPF 55204 e PF 87451). Os cortes não afetaram, na média dos cereais, os valores de fibra bruta, de extrato etéreo, de energia bruta e de atividade ureática, tendo o teor de matéria mineral aumentado com dois cortes. Excetuando aveia-preta e cevada, com os cortes verificou-se incremento nos percentuais de proteína bruta. Entretanto, observou-se, na média dos cereais, redução com os cortes nos teores de extrativos não-nitrogenados. Os resultados obtidos conduzem à possibilidade de uso dos cereais de inverno para duplo propósito, com aproveitamento dos grãos sem maiores prejuízos à sua composição química.<br>An increased demand for activities integrating crop-cattle production in the Rio Grande do Sul plateau has contributed to a dual purpose use (forage and grain) of winter small grains. Therefore, a better knowledge on how to use these cereals for pasture, as well as on the economic value of grains and their potential use in human and animal foods, is necessary. The objective of this study was to evaluate the influence of cuts (one and two) simulating cattle grazing in the chemical composition of the grain of white oats (UPF 14), black oats Avena strigosa (comum), rye (BR 1), triticale (BR 4), barley (BR 2), and wheat (IPF 55204 and PF 87451). In the cereal average, cuts did not affect the values of crude fiber, fat, crude energy, and ureatic activity and led to increased levels of ash with two cuts. Excepting black oats and barley, an increase in crude protein percentuals with the cuts was observed. Nevertheless, a reduction in non-nitrogeneous substances was observed in the cereal average, with the cuts. These results suggest the possibility of using the winter cereals for dual purpose, using the grains without greater damages in their chemical composition