Effect of early lactation feeding strategy on production, metabolic and endocrine responses of primiparous dairy cows

• Published in: Journal of animal science 2016-10, Vol.94, p.638-638
• Main Authors: Carriquiry, M, Cariani, M, Jasinsky, A, Adrien, M L, Mattiauda, D A
• Format: Article
• Language: English
• Subjects: Adiponectin; Alfalfa; Cattle; Cow's milk; Dairy cattle; Data processing; Effects; Feeding; Grazing; Hydrocortisone; Insulin; Lactation; Leptin; Lipolysis; Milk; Milk production; Milking; Pasture; Postpartum; Strategy; Studies; Total mixed rations
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/jam2016-1323

Primiparous Holstein cows (n = 18; 528 ± 40 kg BW, 3.2 ± 0.2 BCS) calved in fall were used in a randomized block design to study the effect of feeding strategy on production, metabolic, and endocrine responses in early lactation. At calving, cows were assigned within block to 1 of 2 feeding strategies during the first 65 d postpartum (DPP). Feeding strategies were either (G0) total mixed ration (TMR) ad libitum (17 kgDM/d offered; 70% forage, 30% concentrate) or (G1) grazing of alfalfa (Medicago sativa; 6-h am grazing in 3-d strips; pasture allowance = 20 kgDM/d) + TMR (70% of ad libitum TMR; 12 kgDM/d offered). Both groups consumed 2.2 kgDM/d of a commercial ration at each milking. Cows were milked twice a day, milk yield was recorded daily and samples were collected weekly for milk composition. Cow BW and BCS were recorded every 2 wk from -40 to +65 DPP. Blood samples were collected for metabolite and hormone analyses at -7 ± 2 and +42 ± 3 DPP. Data were analyzed as repeated measures with a mixed model that included: feeding strategy, DPP, and its interaction as fixed effects, block as random effect and calving date as a covariate. Milk yield (26.7 vs. 25.1 ± 0.58 kg/d), total solids (3.38 vs. 3.1 ± 0.09 kg/d) and NEL output (20.9 vs. 19.2 Mcal NEL/d) tended (P < 0.07) to be greater for G0 than G1 cows, being differences more marked from +30 to +60 DPP. Cow BW and BCS did not differ (P > 0.30) between feeding strategies. Concentrations of plasma NEFA decreased (P < 0.01) at +42 DPP when compared to -7 DPP and at +42 DPP tended (P = 0.10) to be greater for G0 than G1 cows (0.34 vs. 0.25 ± 0.03 mmol/L. Plasma BHB concentration at +42 DPP was greater (P = 0.02) for G0 than G1 cows (0.46 vs. 0.27 ± 0.05 mmol/L) as it decreased from -7 to +42 DPP only in the latter group. In contrast, plasma insulin was reduced (P = 0.05) in G0 than G1 cows at +42 DPP (11.7 vs. 7.2 ± 1.3 uU/mL) as it increased from -7 to +42 DPP only in the latter group. Concentrations of cortisol, leptin and adiponectin were not different (P > 0.20) at -7 than +42 DPP and neither differed between feeding strategies at +42 DPP. Metabolic and endocrine profile would indicate a greater lipolysis in early lactation in G0 than G1 cows which would be probably associated to their greater milk production.