Effect of supplemental dietary slow‐release urea on growth performance and physiological status of dairy heifers. (30th April 2018)

• Record Type: Journal Article
• Authors: Zhang, Jiaojiao; Qiu, Qiang; Shang, Zhanhuan; Liu, Shujie; Degen, Allan; Li, Shanshan; Yan, Qi; Wang, Weiwei; Jing, Xiaoping; Bai, Yanfu; Ding, Luming
• Is Part Of: Animal science journal. Volume 89:Number 7(2018)
• Page Start: 966
• Page End: 971
• Publication Date: 2018-04-30
• Subjects: blood biochemical indices -- dairy heifer -- dry matter intake -- growth performance -- slow‐release urea; Animal culture -- Periodicals; Livestock -- Periodicals; 636
• DOI: 10.1111/asj.13010
• Languages: English
• ISSNs: 1344-3941

Abstract

Abstract: We examined the effect of supplemental dietary slow‐release urea on the growth performance and physiological status of 16 dairy Holstein heifers (10 months of age, 322 ± 10 kg). The heifers were offered a formulated isocaloric and isonitrogenous 70:30 roughage : concentrate ration and were assigned randomly to one of four levels of slow‐release urea supplementation (0% [U0 ], 1% [U1 ], 1.5% [U1.5 ] and 2% [U2 ] dry matter [DM]). The total study lasted 95 days, which included a 20 days adaptation period. Dry matter intake (DMI) of U2 was lower than the intakes of U0 and U1 ( p < .05), while average daily gains (ADG) of U1 and U1.5 were higher than U0 and U2 ( p < .05). Rumen volatile fatty acids concentration did not differ among the four treatments, while ammonia nitrogen concentration increased with an increase in urea level ( p < .05). Serum blood urea nitrogen concentration was lower in U1.5 than in U0 and U2 while serum free fatty acids concentration in U2 was higher than in the other three treatments ( p < .05). We concluded that the addition of urea at a level of 1.5 to 2.0% DM resulted in a reduction in DMI but the addition of 1.0%–1.5% urea resulted in the highest ADG, with no negative effects on rumen fermentation and health status of the calves.