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- Title
PRODUCCIÓN Y COMPOSICIÓN QUÍMICA DE LECHE DE VACAS F<sub>1</sub> HOLSTEIN X CEBÚ SUPLEMENTADAS CON DOS FUENTES DE NITRÓGENO NO PROTEICO.
- Authors
Herrera-Angulo, Ana María; Mora-Luna, Robert Emilio; Isea-Chávez, Juan Carlos; Eslava-Tovar, José Fernando; Darghan, Aquiles Enrique
- Abstract
In order to evaluate the effect of two non-protein nitrogen sources (NPN) on average daily gain (ADG), changes in body condition (CBC), total milk yield (TMY) and their chemical composition (crude protein: MP, true protein: MTP, fat: MF, and urea: MU) in lactating cows, an experiment was conducted in Venezuelan southwestern with 31 F1 Holstein x Zebu cows with two or more calvings, 419 ± 46 kg body weight, 51 ± 18 days (d) in milk, 17.1 ± 3.3 kg milk·animal-1·d-1 and grazing on pastures established Urochloa humidicola, U. decumbens and U. brizantha, divided into two groups and assigned for 91 d to two treatments: 1) 59 g·animal-1·d-1 of urea as a source of NPN for rapid degradation (RD), and 2) 64 g·animal-1·d-1 of Optigen II® as a controlled release of NPN (CR). The ADG and CBC were evaluated every 28 d; the TMY was determined by weekly weighing of milk. The chemical composition of milk was evaluated every 14 d a.m./ p.m. It was used a completely randomized design with repeated measures over time. There were no differences (P>0.05) between NPN-RD and NPN-CR in the variables ADG (504.4 ± 97.5 and 524.9 ± 90.3 g·animal-1·d-1, respectively), CBC (0.002 ± 0.001 and 0.004 ± 0.001, respectively), TMY (15.2 ± 0.62 and 14.7 ± 0.60 kg·animal-1·d-1, respectively) and MU (40.9 ± 0.74 and 41.2 ± 0.79 mg·100 mL-1). The MP with NPN-CR was higher (P<0.05) to NPN-RD group (3.05 ± 0.03 and 2.95 ± 0.03 %, respectively). The MF showed significant differences (P<0.01) between a.m. (3.62 ± 0.12%) and p.m. (3.96 ± 0.12%) milking. The NPN-CR, favored the synthesis of crude protein in milk under test conditions without increase of the milk true protein.
- Publication
Revista Cientifica de la Facultade de Veterinaria, 2017, Vol 27, Issue 2, p119
- ISSN
0798-2259
- Publication type
Article