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Effect of a low forage diet on the yields of milk and milk components and feed efficiency of mid-lactation dairy cows.

A. N. Negreiro




Effect of a low forage diet on the yields of milk and milk components and feed efficiency of mid-lactation dairy cows.
A. N. Negreiro*, A. L. Lock. Michigan State University East Lansing, MI.

Examining the effect of lower forage diets and alternative fiber sources in lactating dairy cow diets is important since forage quality and quantity can vary greatly depending on growing conditions, years, and locations. Therefore, we determined the effect of feeding diets similar in NDF, starch, and CP with differing amounts of forage on the yields of milk and milk components of mid-lactation dairy cows. Thirty-two Holstein cows (132 � 68 DIM) were used in a crossover design with 2 consecutive 28-d periods, with sample and data collection during the final 5 d of each period. Treatment diets were: 1) control diet (CON) containing high forage (51.4% diet DM; forage NDF 18% diet DM) and no supplemental fat or supplemental amino acids (RUP 6.67% diet DM; RDP 10.4% diet DM); and 2) low forage diet (LF) containing low forage (31.6% diet DM; forage NDF 11.2% diet DM), including supplemental fat (1.5% diet DM; 82% C16:0-enriched supplement) and supplemental amino acids (RUP 7.01% diet DM; RDP 9.69% diet DM). Diets were balanced for similar NDF (29% diet DM), starch (26.5% diet DM), and CP (16.9% diet DM). The statistical model included the random effect of cow and fixed effects of diet, period, and their interaction. Results are presented in the sequence CON vs LF. There was no effect of treatment on milk yield (45.4 vs 46.1 kg/d, P = 0.34), milk fat content (3.95% vs 3.99%, P = 0.38), or BW (704 vs 703 kg, P = 0.83). Compared with CON, LF decreased DMI (34.7 vs 28.6 kg/d, P < 0.01) and increased milk fat yield (1.78 vs 1.84 kg/d, P = 0.02), milk protein yield (1.47 vs 1.56 kg/d, P < 0.01), milk protein content (3.24% vs 3.41%, P < 0.01), ECM (48.3 vs 50.2 kg/d, P < 0.01), feed efficiency (ECM/DMI; 1.41 vs 1.77 kg/d, P < 0.01), and BCS (3.2 vs 3.3, P = 0.02). Our results demonstrate that feeding a low forage diet supplemented with amino acids and a palmitic acid-enriched supplement increased feed efficiency through decreased DMI and increases in the yields of milk fat and protein, without changes in BW.

Keywords: forage, amino acid, fatty acid.

Biography: Ariana is originally from Fort Lauderdale, FL and earned her bachelor's in animal science at Michigan State University. Currently, she is a master's student with Dr. Adam Lock researching the effects of fatty acid and amino acid supplementation in mid-lactation dairy cows.