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Nitrogen efficiency of dairy sheep supplemented with crude glycerin diluted in water*
Natália C. Alves1**, José A. Junior2, Felipe S. Santos2, Hemilly C. M. Sá3, Iran Borges2, Gilberto
L. Macedo4, Tassia L. T. M.2, Jizênio A. S. Passos1, Juliana A. Favato1, Celso H. F. Paiva1
*Part of master thesis of the third author 1Undergraduate student Veterinary School of Federal
University of Minas Gerais; 2Animal Science Department, Veterinary School of Federal
University of Minas Gerais;3Animal Science Department, Federal University of Sergipe; 4Animal Science Department, Federal University of Uberlândia;
**Federal University of Minas Gerais, Av. Presidente Carlos Luz, 4466, São Francisco, CEP
31250-810, Belo Horizonte, MG, Brazil; [email protected]
The Crude Glycerin (CG) expressed a potential for use in diet of dairy ruminants. Recent
renewable energy use policies have promoted a CG surplus. This byproduct can be applied to
ruminant nutrition as a cheap source of energetic food, with easily storage and delivery. The use
of CG can provide balance between energy and protein, according to ruminal degradation kinetics,
that results in maximum microbial growth, in lower urinary losses of energy and nitrogen, and
optimization of dietary nitrogen use for casein synthesis. The objective of this study was to
evaluate the effects of the inclusion of crude glycerin diluted in water for dairy sheep on nitrogen
(N) efficiency for milk yield. Were used 20 Lacaune x East Friesian lactating dairy ewes, between
three and four years’ age, with the average weight of 62.68 ± 5.95kg. The animals remained in
individual pen with free access to water, and concentrate and roughage were provided separately.
The sheep were distributed in a completely randomized design, in four treatments differed as to
supplementary CG intake diluted in water: zero, 1.5%, 3.0% and 4.5% of dry matter intake. Ewes
were Machine milked once a day at 15:00. The lactation persisted to 17 weeks. The diets were
formulated to meet the nutritional requirements according to the NRC (2007). Weekly an
individual sample of 40 ml of milk was collected, and sent to the Milk Quality Laboratory (Lab
UFMG) to evaluate the amount of nitrogen present in the milk. Nitrogen efficiency was calculated
as the ratio of total milk Nitrogen (g day -1) and the total Nitrogen intake (g day -1). Data were
submitted to analysis of variance, F test (α<0.05), decomposed into orthogonal contrasts and
polynomial regression. N-efficiency, in the order of CG inclusions, was 18.03 %; 17.14 %; 19.81
%; 18.74 %. There was a linear increase in N-efficiency (α<0.01) in function of the CG
supplementation. Probably the CG provided a better use of ruminal nitrogen by the macrobiotic,
with less losses of ammonia. The nitrogen efficiency in production of milk can be improved by
supplementing crude glycerin diluted in water for dairy sheep.
Keywords: biofuels, ewe, glycerol, protein.
Acknowledgments: Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq),
Fundação de Amparo à Pesquisa do estado de Minas Gerais (FAPEMIG) and Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior (CAPES).
