Daily methane emission profile in Holstein heifers fed rice straw. (Author: G. D. Cruz, P. H. Hai, S. Polyorach, N. Anantassok, P. Beelen, H. D. Rosa, and E. Kebreab) |
In South East Asia, rice straw is the principal crop residue fed to livestock; it is estimated that 40% of total rice straw produced goes to animal feed. Rice straw is a high lignin, high silica and low digestibility feedstuff, therefore a method to increase its nutritional quality would benefit animal production |
G. D. Cruz*1, P. H. Hai2, S. Polyorach3, N. Anantassok3, P. Beelen4, H. D. Rosa5, and E. Kebreab1 (1) University of Califor-nia, Davis, (2) Institute of Agricultural Science for Southern Vietnam, Hochiminh City, Vietnam, (3) Khon Kaen University, Khon Kaen, Thai-land, (4) Federal University of Alagoas, Rio Largo, Brazil, (5) Sao Paulo State University, Botucatu, Brazil. Astract In South East Asia, rice straw is the principal crop residue fed to livestock; it is estimated that 40% of total rice straw produced goes to animal feed. Rice straw is a high lignin, high silica and low digestibility feedstuff, therefore a method to increase its nutritional quality would benefit animal production. The objectives of the study were to 1) improve the utilization of rice straw by increasing dietary nitrogen or energy availability and consequently reduce methane emissions, 2) analyze the daily profile of methane measured in ventilated hood chambers (VHC) and 3) investigate intake variability of heifers in VHC compared with group pen. Nine Holsteins heifers were fed in a 3 × 3 Latin square design, with 3 dietary treatments and 3 periods. Animals were fed twice daily at 0900 and 1700 h. Treatments were: control (14.3 CP% and 2.35 Mcal ME/kg DM), high energy (14.2 CP% and 2.45 Mcal ME/kg DM) and high protein (16.5 CP% and 2.36 Mcal ME/kg DM). Each period consisted of 14 d of adaptation and 1 d in the VHC. During the adapta-tion period heifers were kept in a group pen equipped with Calan gate system to measure individual feed intake. Feed offered and refused in the VHC was weighted individually. Dry matter intake (DMI) of the day that animals were in the VHC was used as a covariate to analyze the total methane emitted. Increase in nitrogen or in energy in the diet did not have an effect on daily methane emission (P ≥ 0.35), with heifers in control, higher energy and high protein treatments emitting a daily average of 396, 393 and 414 g/d, respectively. A 37% decrease in DMI between heifers in VHC and previous day in group pen was observed (6.4 vs. 10.2 kg/d, P < 0.001, respectively). Methane emission peaks occurred between 1 to 1.5 h after feeding, the morning peak averaged 20 g/h and the afternoon 24 g/h. Daily lowest values were observed early morning, 1 to 2 h before feeding with average values of 10g/h. Even though heifers were provided with the best management condi-tions during the VHC day, DMI was drastically reduced, which may have affected methane productions. Caution needs to be taken when making inference in methane production data when using VHC method and when few hours of observation are extrapolated to daily emission. Key Words: dairy heifers, methane emission, rice straw J. Anim. Sci. Vol. 90, Suppl. 3/J. Dairy Sci. Vol. 95, Suppl. 2 |
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