Forage quality and digestibility for calculation of enteric methane emission from cattle
2016
Degola, L., Latvia Univ. of Agriculture, Jelgava (Latvia). Inst. of Agrobiotechnology | Trupa, A., Latvia Univ. of Agriculture, Jelgava (Latvia). Inst. of Agrobiotechnology | Aplocina, E., Latvia Univ. of Agriculture, Jelgava (Latvia). Inst. of Agrobiotechnology
Forage quality is a significant factor that affects methane (CH4) production in the cattle intestinal tract. Forage quality, level of concentrate, diet digestibility and feed intake are interrelated and directly affect enteric CH4 production in the rumen. At the Latvia University of Agriculture Scientific Laboratory of Agronomic Analysis the chemical content of animal feed was analysed; together 93 feed samples from all regions of Latvia. The cattle feed samples were collected from January until December in 2015. The chemical analysis of animal feed was made according to generally accepted zootechnical methods of analysis: dry matter (DM) %, crude protein (CP) %, insoluble protein, %, soluble protein, %, under graded intake protein (UIP) %, crude fibre (CF) %, acid detergent fibre (ADF) %, neutral detergent fibre (NDF) %, ash %, Ca and P %, according ISO 5983, ISO 6490/2 and ISO 6491 standards, and net energy for lactation (NEL, MJ• kgE-1 DM) were calculated. Digestibility was determined using the cellulase method. The results show that forages vary significantly in the NDF content and digestibility. Depending on the maturity level of green mass in the harvesting period, the content of NDF in hay was within 51-71 %, in silage 24-48 %, in haylage 38-62 % and in total mixed ration (TMR) 30-45 % of DM. The average digestibility of forage (with the cellulase method): for hay-52.3- 53.8 %; for grass silage with preservative 65.2 ± 6.13 %, without preservative 62 .8 ± 4.93 %; and for corn silage, respectively 71.1 ± 0.6 %, 68.2 ± 3.1 %; for haylage 62.6 ± 4.08 %, for TMR 71 .7 ± 5.68 %. The nutritional value of the analysed forage was good or average. There was no significant difference between the feed digestibility indicators as defined by both the chemical method and the method of calculation. So, there is no need to make the forage digestibility determination in the laboratory with the cellulase method, but the formula (DDM, % = 88.9 – (0.779 x A DF %) can be used, where the digestibility is calculated from the ADF content in feed.
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