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Energy Metabolism Peripheral Indicators in Total Mixed Ration vs. Component Fed Dairy Cows in a Competitive Environment
This objective was to establish effects of total mixed ration (TMR) delivery vs. component feeding of forage and concentrate (CF) on selected peripheral blood markers of energetic in lactating dairy cows in a competitive housing environment. Twelve multiparous (650 ± 55 kg body weight; 45 ± 20 days in milk; mean ± SD) and twelve primiparous (579 ± 49 kg body weight; 59 ± 36 days in milk) lactating Holstein cows in free houses were monitored continuously in a completely randomized design experiment for three months. A 10-d pre-trial adaptation period was allowed before data collection. Cows were offered an experimental diet (barley grain and corn silage-alfalfa hay based) as either TMR or CF of forage and concentrate for the entire experiment. The forage to concentrate ratio (dry matter based) was 50:50, allowing 5-10% daily orts. Cows were fed 3 times daily at 0530, 1330, and 2130 h. The daily TMR was divided to three equal portions and each portion was fed at each feed delivery. The CF was divided to one portion of forage fed at 0530 h, and two equal portions of concentrate fed at 1330 and 2130 h. Cows were milked 3 times daily at 0500, 1300, and 2100 h. Tail vein blood samples were taken weekly before milking. Statistical data analysis was conducted with Mixed Models. Feeding CF vs. TMR increased (P<0.05) peripheral blood concentrations of glucose (68 vs. 62 mg/dl) and BHBA (0.41 vs. 0.32 mmol/L), but did not affect (P>0.15) those of NEFA (0.25 vs. 0.35 mmol/L) and urea nitrogen (13.6 vs. 14.1 mg/dL), respectively. Neither parity nor its interaction with treatment affected peripheral blood metabolites. The results do not suggest that feeding TMR instead of CF improves energetic of lactating cows. Findings provide evidence to more insightfully contemplate CF for high-producing dairy cows in postmodern times.
Keywords: Component feeding, Metabolism, Dairy cow