Author
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Mertens, David |
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Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only Publication Acceptance Date: 5/30/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: This study was designed to test the hypothesis that equal performance would be obtained from a variety of forages if rations for lactating dairy cows were formulated to contain similar NDF concentrations. Sixty Holstein cows, averaging 90 days in lactation and 35.1 kg milk/d, were blocked by parity and initial milk production and assigned to one of five silage- containing rations: sorghumXsudan hybrid (SS), orchardgrass (OS), alfalfa (AS), wheat (WS), or corn (CS). Dry matter, CP, and aNDF (amylase treated, ash-free NDF) concentrations of the forages were: 40.2, 12.8 and 54.8; 44.8, 15.5 and 48.4; 57.9, 17.2 and 45.2; 51.7, 10.2 and 54.4; and 42.1, 8.3 and 41.6%, for SS, OS, AS, WS, and CS, respectively. Total mixed rations contained 8% roasted soybeans and were formulated to have 31% aNDF and 18% CP using high moisture corn and soybean meal. Cows were fed a covariate ration containing a mixture of all silages for 2 weeks followed by their assigned ration for 12 weeks. There were no differences in average intake, milk production, or milk composition among treatments. The initial hypothesis was not rejected; it appears that forages of differing qualities can result in equal performance if fed in rations that contain similar NDF. It is recommended that dairy rations be balanced for NDF concentration rather than forage to concentrate ratio to adjust for differences in forage quality. |
