VIBQGEBW

3330

7 janvier 2021 17:00

15 avril 2021 11:06

Dairy heifers developed in certified organic programs, especially those utilizing pasture-based management schemes, have lower rates of gain than heifers raised in conventional production systems. This study investigates the effects that different forages in a rotational grazing system have on the development of organically raised dairy heifers. Over 3 years, 210 yearling Jersey heifers were assigned to one of nine treatments, including a conventional dry lot control (TMR) or one of eight pasture treatments. Pasture treatments included: tall fescue (TF), meadow bromegrass (MB), orchard grass (OG), perennial ryegrass (PR) and each individual grass interseeded with birdsfoot trefoil (BFT). Every 35 days, over a 105-d period, heifers were weighed, measured for hip height, and blood samples were collected to determine serum insulin-like growth factor-1 (IGF-1) and blood urea nitrogen (BUN) concentrations. Fecal samples were collected to determine fecal egg count (FEC). Heifer body weights (BW), BUN, and IGF-1 concentrations were affected by treatment (p < 0.01) when analyzed over time. Heifers on mixed legume-grass pastures (MIX) tended to have greater BW compared to heifers on monoculture grass pastures. Heifers receiving TMR or PR+BFT had increased BW gain (p < 0.05) over the 105-d period than heifers grazing TF+BFT, OG, PR, MB, or TF. Whereas, at d 105, heifers receiving TMR, PR+BFT, OG+BFT, or MB+BFT had greater (p < 0.05) BW than heifers receiving TF. Heifer hip-height, conception rate, and FEC were not affected (p > 0.05) by pasture type or treatment when analyzed over time. Whereas, heifers grazing MIX pastures had greater (p < 0.01) BUN compared to heifers grazing MONO pastures. These results show that the addition of BFT to pasture improves growth of replacement heifers. Grass pastures interseeded with BFT may be a sustainable option to achieve adequate growth of dairy heifers raised in a pasture scenario.

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• AB - Spécifique
• FREDO alimentation animale
• FREDO fourrage et prairie
• FREDO mode élevage, bien-être et qualité
• FREDO santé animale
• GEO Etats-Unis
• performance

2020-08-01

1 août 2020