Effect of Partial Replacement of Green Grass by Urea Treated Rice Straw in Winter on Milk Production of Crossbred Lactating Cows

M V Sanh,L V Ly,H Wiktorsson

doi:10.5713/ajas.2002.543

Abstract

Fresh elephant grass was replaced by urea treated rice straw (UTRS) to evaluate the effects on milk production of crossed lactating cows. A total of 16 crossbred F1 cows (Holstein Friesian × Vietnamese Local Yellow), with a body weight of about 400 kg and lactation number from three to five, were used in the experiment. The experimental cows were blocked according to the milk yield of the previous eight weeks and divided into 4 homogenous groups. The experiment was conducted with a Latin Square design with 4 treatments and 4 periods. Each period was 4 weeks, with 2 weeks of feed adaptation and 2 weeks for data collection. The ratio of concentrate to roughage in the ration was 50:50. All cows were given constant amounts of elephant grass dry matter (DM), with ratios of 100% grass without UTRS (control treatment 100G), and 75% grass (75G), 50% grass (50G) and 25% grass (25G) with ad libitum UTRS. Daily total DM intake on 100G, 75G, 50G and 25G was 12.04, 12.31, 12.32 and 11.85 kg, and the daily ME intake was 121.6, 121.5, 119.4 and 114.3 MJ, respectively. The daily CP intake was similar for all treatments (1.85-1.91 kg). There was a difference (p<0.05) in daily milk yield between the 25G and the 100G and 75G (11.7 vs. 12.6 and 12.5 kg, respectively). Milk protein concentration was similar for all treatments, while a tendency to increased milk fat concentration following the increase of UTRS ratio was observed. The cows gained 4-5 kg body weight per month and showed first oestrus 3-4 months after calving. The overall feed conversion for milk production was not affected by ratio of UTRS in the ration. It is concluded that replacement of green grass by UTRS with a ratio of 50:50 for crossbred lactating cows is as good as feeding 100% green grass in terms of milk yield, body weight gain and feed conversion. UTRS can preferably replace green grass in daily rations for crossbred dairy cows in winter to cope with the shortage of green grass, with the ratio 1:1. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 4 : 543-548)

Highlights

Rice straw is the most important feed source to replace scarce green grass
This study aimed to evaluate the effects of partial replacement of cultivated green grass by utilization are therefore considered the straw (UTRS) on milk production of crossbred lactating cows in zero grazing systems and to recommend the ratio of green grass, which can be replaced by UTRS for feeding dairy cows during the winter period
The feeding standards were based on the National Research Council recommendations (NRC, 1988): for maintenance: 0.56 MJ metabolisable energy (ME) and 3.5 g crude protein per 1 kg BW0.75 and 16 g Ca, 11 g P for a 400 kg cow; for milk production: 5.19 MJ ME, 90 g crude protein, 3.21 g Ca and 1.98 g P per 1 kg fat corrected milk (FCM) produced; for weight gain: 35.77 MJ ME and 320 g crude protein per 1 kg weight gain, for weight loss: -34.52 MJ ME and -320 g crude protein per 1 kg weight loss

Summary

Introduction

Rice straw is the most important feed source to replace scarce green grass. It is readily available locally throughoutDairy production in Vietnam has no long tradition, is the country, with a total amount of 25-30 million tons still limited, and mainly based on crossbred cattle. Rice straw is the most important feed source to replace scarce green grass. A small part has been urban and peri-urban areas, dairy cows are often kept under used as feed for local cattle and buffalo which mainly are roof and fed planted or natural grasses in cut and carry used for draught. Rice straw is low in available energy, systems, by-products from industrial processing and protein and vitamins and has an imbalance of essential compound feed. Dairy cows are traditionally minerals, but it contains a large pool of structural kept in semi-intensive systems and fed mainly natural carbohydrates which can potentially be degraded by rumen grasses, crop residues and small amount of concentrates. Dairy cows are traditionally minerals, but it contains a large pool of structural kept in semi-intensive systems and fed mainly natural carbohydrates which can potentially be degraded by rumen grasses, crop residues and small amount of concentrates. microbes into volatile fatty acids, and as energy

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Results