Macromineral requirements by beef cattle under pasture supplementation

Abstract

-The objective of this work was to determine macromineral requirements by Zebu steers grazing Brachiaria decumbens supplemented with concentrate. It was used 24 non-castrated steers, at an average age of 7 months and at initial average weight 180 kg. Eight control animals were slaughtered for determining initial body composition. The 16 remaining animals were divided in four four-animal plots, in a complete random design. Each plot received mineral mixture or supplements at the levels 0.75; 1.50 or 2.25 kg/animal/day. The right half-carcass of eight animals, two per group, was dissected in muscle, fat and bones and all body constituents were weighted for determination of empty body weight and body composition. Net requirements of calcium and phosphorus for an animal at 400 kg body weight were 11.13 g and 5.40 g, respectively. To estimate dietary requirements of maintenance and after, sum them to dietary requirements for gain in order to obtain total dietary requirements, it was adopted endogenous losses and bioavailability present in literature for each mineral macroelement. Total dietary requirement for calcium, phosphorus, magnesium, sodium and potassium for a 400-kg BW animal with 1.0-kg daily weight gain were 34.59; por grupo, foi dissecada em músculo, gordura e ossos e todos os constituintes do corpo foram pesados para determinação do peso de corpo vazio e da composição corporal. As exigências líquidas de cálcio e fósforo para um animal de 400 kg de peso corporal foram, respectivamente, 11,13 g e 5,40 g. Para estimar as exigências dietéticas de mantença e, posteriormente, somá-las às exigências dietéticas para ganho, no intuito de se obter as exigências dietéticas totais, foram adotadas as perdas endógenas e a biodisponibilidade presentes na literatura para cada macroelemento mineral. As exigências dietéticas totais de cálcio, fósforo, magnesium, sódio e potássio para um animal de 400 kg de PC com ganho diário de 1,0 kg foram, respectivamente, 34,59; 17,36; 7,82; 5,19 e 41,11 g/dia. As exigências em macrominerais de bovinos de corte sob suplementação a pasto são semelhantes às recomendadas pelo BR-Corte para bovinos de corte em confinamento.Palavras-chave: cálcio, exigências nutricionais, fósforo, suplementação, zebuínos Revista Brasileira de Zootecnia

Nutritional requirements of energy, protein and macrominerals for maintenance and weight gain of young crossbred Nellore × Holstein bulls on pasture

“…The amount of P decreased as body weight increased (Table 8) EBW found by Sales et al (2011), working with crossbred Nellore/Holstein animals. Values of Mg decreased little as body weight increased -0.42 for 0.40 g/kg of EBW -, which is very close to the one recommended by the ARC (1980), which allows constant Mg net requirement of 0.45 g/kg EBW, regardless of animal weight.…”

“…CSIRO (2007) has recommended that the maintenance requirements for beef cattle raised on pasture be from 10 to 50%, and in function of the distance traveled, the availability of pasture and slope of the terrain. Some studies on nutritional requirements for cattle raised on pasture (Zervoudakis et al, 2002;Fregadolli, 2005;Moraes et al 2009;Paixão, 2008;Sales et al 2010;Sales et al, 2011) have been developed in Brazil, but the amount of information available is still considered small for the development of equations that are considered as reliable for use in diet formulation programs, especially regarding the supplementation of these animals.…”

Nitrogen Fertilization of Marandu Palisadegrass under Different Periods of Deferment

“…Contradictory effect was obtained by [19] that found similar mass of leaves from the deferral beginning to the quantity obtained at the end of the analyzed period. The author [20] verified that the green leaf blade in B. decumbens pastures decreased from 1,638 to 891 kg DM ha -1 during the pasture period use in autumn due to the increase in stem length and maintenance of the live leaves number in the vegetative tillers. More attention must be paid to the grass quality for animal grazing, considering that, the green leaf blade is the morphological component with the best nutritive value [21].…”

Suplementação mineral para bovinos de corte – uma revisão sistemática

“…O sulfato de ferro irá diminuir a absorção de fósforo e de cobre nos animais (Peixoto et al, 2005). Sales et al (2011) avaliaram as exigências dietéticas de bovinos com ganho diário de 1,0 Kg, para bovinos com 400 Kg de peso corpóreo e as exigências foram de 34,59 g de cálcio, 17,36 de fósforo, 7,82 de magnésio, 5,19 de sódio e 41,11 de potássio por dia.…”