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Abstract

ABSTRACT


A new midrib corn hybrid called Master Graze MG has been recently introduced in the US as a new forage source for cattle. However, before recommending its use to livestock producers, it146s important to evaluate its nutritional value. Therefore, the objective of this study was to evaluate the effects of using MG silage as a forage source in a lactating dairy cow146s diet on feed intake, milk yield, milk composition and nutrient digestibility. Sixteen Holstein cows, in mid lactation 12019 DIM, were divided into four treatment groups n 4 cowstreatment and fed treatment diets for 4 consecutive periods with each period consisted of 21 days. The cows on the control diet CON were fed a 6040 forageconcentrate diet dry matter DM basis with corn silage and alfalfa hay as the forage source 11 DM basis. For treatment groups, the MG silage substituted the forage mix at 16 MAS-16, 33 MAS-33 and 50 MAS-50 on a DM basis. All diets were formulated to be isonitrogenous. Cows were fed the treatment diets as a total mixed ration once daily. Substituting the corn silage-alfalfa hay mix with the MG silage at the three tested levels had no effects p0.05 on feed intake or milk production. Milk fat percentages and yields and milk protein percentages and yields were similar p0.05 among treatment diets. Relative to CON diet, the apparent digestibility of DM and OM were higher p0.05 in cows fed the MAS-50 diet and tended to increase p0.11 in cows fed the MAS-16 and MAS-33 diets. The apparent digestibility of NDF in cows fed the MG diets were higher p0.05 than in cows fed the CON diet, with MAS-50 being the highest p0.01. The apparent digestibility of crude protein was higher p0.05 in cows fed the MAS-50 diet in comparison to cows fed the CON diet. In conclusion, the inclusion of MG silage in lactating dairy cow146s diet had no effects on cow146s feed intake, milk production or milk composition but improved the digestibility of nutrients. The MG silage may replace 50 of dietary corn silage-alfalfa hay mix in a lactating dairy cows ration without any adverse effects on lactating dairy cow146s performance.

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