Nitrogen supplementation of corn silages. 1. Effects on feed intake and milk production of dairy cows.

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dc.contributor.author Fonseca, A. J. M.
dc.contributor.author Cabrita, A. R. J.
dc.contributor.author Miranda, I. N. F.
dc.contributor.author Sampaio, C. U. P.
dc.contributor.author Gomes, E.
dc.contributor.author Sousa, G. N. S.
dc.contributor.author Miranda, M. F. S.
dc.contributor.author Dewhurst, Richard J.
dc.date.accessioned 2009-11-03T11:30:39Z
dc.date.available 2009-11-03T11:30:39Z
dc.date.issued 2003-12
dc.identifier.citation Fonseca , A J M , Cabrita , A R J , Miranda , I N F , Sampaio , C U P , Gomes , E , Sousa , G N S , Miranda , M F S & Dewhurst , R J 2003 , ' Nitrogen supplementation of corn silages. 1. Effects on feed intake and milk production of dairy cows. ' Journal of Dairy Science , vol 86 , no. 12 , pp. 4008-4019 . en
dc.identifier.issn 0022-0302
dc.identifier.other PURE: 139584
dc.identifier.other dspace: 2160/3403
dc.identifier.uri http://hdl.handle.net/2160/3403
dc.description.abstract Feed intake and milk production responses to N supplementation of corn silage-based diets were measured in three 3 × 3 Latin square experiments. In each experiment, 9 Holstein cows received total mixed rations (TMR), based on corn silage. In Exp. 1, midlactation cows were used to study effects of diets with different ratios of effective rumen-degradable protein (ERDP; g) to fermentable metabolizable energy (FME; MJ), providing a large deficiency (RL), a slight deficiency (RM), and a slight excess (RH) in relation to the target level of 11 g of ERDP/MJ of FME, respectively, for lactating cows. Diets were formulated to be isoenergetic, and to satisfy the metabolizable protein requirements. In Exp. 2, early-lactation cows were used to evaluate effects of different proportions of quickly and slowly rumendegradable protein (RDP), achieved by replacing soybean meal with urea in the concentrates (0, 0.5, and 1% urea). Experiment 3 investigated effects of synchronizing the availability of FME and ERDP in the rumen. Midlactation cows received a diet containing, on a dry matter (DM) basis, 45% corn silage, 5% ryegrass hay, 35% energy-rich concentrate, and 15% protein-rich concentrate (crude protein: 38% of DM; urea: 2% of DM). The protein-rich concentrate was fed either once (D1) or twice (D2) per day before the meal, or included in the TMR (DU). Treatment RL led to lower DM intake and milk yield, but higher milk production efficiency; there were no significant differences between treatmentsRMand RH. There were no significant treatment effects on DM intake, milk yield, or milk composition in Exp. 2. Manipulating rumen synchrony by altering the timing of feeding affected milk yields, with D1 cows producing significantly less than D2 and DU cows, which were similar. The amount of ERDP in the diet should be matched to the amount of fermentable energy available to maximize intake, milk yields, and the conversion of feed N into milk protein. However, this study showed only small benefits to altering the diurnal pattern of supply of RDP and FME, and only with extreme feeding strategies that would not be used in practice. Urine volume increased in response to increased or unbalanced protein supply. Analysis of the allantoin:creatinine ratio in spot samples of urine was not useful in identifying predicted differences in microbial protein yield from the rumen. en
dc.format.extent 12 en
dc.language.iso eng
dc.relation.ispartof Journal of Dairy Science en
dc.title Nitrogen supplementation of corn silages. 1. Effects on feed intake and milk production of dairy cows. en
dc.type Text en
dc.type.publicationtype Article (Journal) en
dc.identifier.doi http://dx.doi.org/10.3168/jds.S0022-0302(03)74012-0
dc.contributor.institution Institute of Biological, Environmental and Rural Sciences en
dc.description.status Non peer reviewed en


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