The needle test (NT) is a point-of-care test developed in Brazil to evaluate the Phosphorus (P) status in cattle. Based on bone resistance, the NT is a very inexpensive method which allows the diagnosis of any degree of P deficiency in a fast and simple way in vivo and directly on farm. The NT measures three levels of resistance in the transverse process (TP) of the lumbar vertebrae: a) TP that are impenetrable and result in warping of the needle (P healthy animals); b) TP offering some resistance to the penetration (animals with subclinical P deficiency); and c) TP which has minimal resistance to penetration (clinical P deficiency). This manuscript presents results from a series of case studies to evaluate the hypothesis that the NT could be used to assess P status in cattle and assesses the usefulness of results to support decision making on mineral supplementation strategies for grazing cattle. The NT was able to detect the changes in the resistance patterns of the TP, as there was reduction or elevation of P levels in the mineral mixtures. The NT was useful to assist in decision-making for adoption of mineral supplementation strategies better suited for each farm, helping farmers to save money and avoid unnecessary waste of P.
RESUMOMuitas fazendas, situadas em bacias leiteiras, estão migrando da atividade leiteira para a pecuária de corte e tal migração vem sendo feita de forma muitas vezes não criteriosa ou sem assistência técnica. Neste estudo, objetivou-se avaliar a viabilidade econômico-financeira e o risco econômico de diferentes sistemas de cria de gado de corte, explorados em regiões de bacia leiteira. O trabalho consistiu em um estudo de múltiplos casos que tiveram como critério de escolha três sistemas que desenvolvessem atividade de cria. O horizonte de informações econômicas dos sistemas foi de 36 meses e os sistemas de criação foram caracterizados por meio de levantamento de dados realizados em visitas periódicas, utilizando-se questionários previamente elaborados. Foram estimados o valor presente líquido e a taxa interna de retorno do investimento, e realizaram-se as análises de sensibilidade e o risco de cada sistema de criação. Os três sistemas de cria foram viáveis financeiramente por terem VPL positivo a uma taxa de desconto de 6,0% a.a. O retorno da atividade mostrou-se mais sensível aos investimentos realizados na compra de terra e nas matrizes. Os riscos desses sistemas, apesar da possibilidade de mudanças no mercado, foram considerados baixos, tornando-os opções de investimentos atrativas, quando comparados aos rendimentos obtidos com a caderneta de poupança.
The aim of this study was to evaluate the morphological and structural characteristics of deferred Urochloa decumbens Stapf. ‘Basilisk’ grazed by Nellore heifers under two periods of protein and energy supplementation (PES). The experiment was carried out from Jun 21 to Nov 15, 2016, under a completely randomized design and two PES periods (55 [P55] and 147 [P147] days). Forage mass (FM), leaf blade dry mass (LBDM), stem dry mass (SDM), dead material dry mass (DMDM), canopy height (CH), and forage bulk density (FBD) were evaluated. Data were analyzed by the SAS® PROC MIXED procedure and treatment means were compared with the Student's t test (p < 0.05). LBDM was higher for P147 heifers after 21, 84, and 126 days of grazing, similar to those observed after 63 days, and was higher for P55 heifers at 42, 105, and 147 days of grazing. SDM was lower for P147 heifers after 21, 42, 105, and 126 days, and similar in the other grazing periods. Protein and energy supplementation for heifers over 147 days resulted in a lower stem mass of U. decumbens Stapf. ‘Basilisk’ deferred pastures.
Fertility, weight of calves at weaning, and the economic aspects of a breeding herd receiving mineral supplements containing 75 or 12.5 g of phosphorus (P)/kg were measured from 2013 to 2016. No differences in reproduction parameters or weight at weaning were found before and after the adoption of the new scheme of mineral supplementation. Before the study, the annual cost with the formula containing more P was equivalent to 29.3 weaned beef calves; after the P reduction, the annual cost was equivalent to 2.2 to 6.8 weaned calves. After 3 years of supplementation with 12.5 g P/kg no signs of P deficiency were observed. The clinical-nutritional diagnosis of the herd indicated no cause-effect of P content of mineral supplements upon fertility or performance of healthy cows, demonstranting that the adequate forage allowance was enough to meet most P required by the cows.
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