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Wageningen University (2000)

Use of napier grass to improve smallholder milk production in Kenya

Muia, J. M. K.

Titre : Use of napier grass to improve smallholder milk production in Kenya.

Auteur : Muia, J. M. K.

Université de soutenance : Wageningen University.

Grade : Doctor of Philosophy (PhD) 2000

In Kenya, dairy production is mainly in the medium and high potential agricultural areas, which occupy about 17 % of the country’s land. Due to high population pressure in these areas, smallholders (2-3 ha) form 80 % of the population. Napier grass (NG) has been identified to be a suitable fodder for these areas due to its high dry matter yield. The current recommendation to feed NG to cows at a height from 60 to100 cm (age, 6-10 weeks) does not take into account factors such as amount of rainfall which may influence yield and quality of the grass. Therefore poor quality and inadequate amount of feeds available to cows are common problems resulting in low levels of milk production (3-5 kg cow -1day -1). Although supplementation is advocated to improve milk production on NG based diets, concentrates are too expensive and high-protein legumes and fodder trees are not available in adequate quantities for supplementation of cows. As a consequence farmers are using poultry litter as an alternative and cheap sources of protein. Information on home-made concentrates using poultry litter as a source of protein, which amounts to supplement, what levels of milk production to expect and economics of production in the wet and dry seasons is therefore required.The overall objective of the study was to improve smallholder milk production in the medium and high rainfall areas through utilization of napier grass at optimal maturity and supplementation using poultry litter based concentrate. A review paper indicated the need to identify specific optimal stages of maturity for feeding NG to cows in the medium and high rainfall areas and that more work on milk production should establish technical and economic levels of supplementation. Digestibility was improved by supplementing NG at early maturity (120 g CP kg -1DM) with soyabean meal. This implies that feeding young grass to animals will not support optimal rumen microbial protein yields resulting in low production levels. Hence the need to identify stage of maturity with optimal amounts of energy and protein. It was shown, based on crude protein : digestible organic matter ratio, that NG should be fed earlier in medium (height, 50-60 cm ; age, 7-8 weeks) than high (height, 130-140 cm ; age, 9-10 weeks) rainfall areas. The digestibility of NG was accurately estimated from fibre fractions (r 2= 0.86 ; rsd = 23.56 ; P < 0.001) or crude protein content (r 2= 0.71 ; rsd =27.85 ; P < 0.001) on-station. Also, its dry matter yield was accurately estimated from age (r 2= 0.89 ; rsd = 1.27 ; P < 0.001) or height (r 2=0.85 ; rsd = 1.54 ; P < 0.001) on-station. Farmers could use equations from this study to accurately estimate dry matter yield from height (r 2= 0.51 ; rsd =0.77 ; P < 0.01) or age (r 2= 0.39 ; rsd = 0.86 ; P < 0.01) of NG in the high rainfall areas.Information on rumen degradation and estimated intestinal protein digestion indicated that supplementing cows fed NG with sunflower seed meal based concentrate (SFBC) or purchased concentrate would support moderate milk yields. However, supplementation with poultry litter or concentrate compounded using poultry litter (PLBC) as a source of protein would result in only low milk yield. To sustain the same level of production, cows fed NG at advanced maturity (dry seasons) should be offered supplements containing about 30 g kg -1DM more of protein digested in the intestines than cows fed the grass at the recommended medium maturity (wet seasons). High feed intake and concentration of volatile fatty acids were achieved at rumen ammonia concentration levels below the level of 100 mg l -1when steers fed NG were supplemented with PLBC or SFBC. The acetate : propionate ratios (3.6-3.9 : 1) for these diets were lower than the value required for maintaining milk butter fat content. To improve on feed intake and digestion, PLBC should be supplemented to cows fed NG at medium maturity while SFBC should be used on cows fed the grass at advanced maturity.It was not profitable, at the current market prices, to produce milk from NG at advanced maturity (dry seasons). Maximum profit was achieved when cows fed NG at medium maturity (wet seasons) were supplemented with 1 kg of dry matter of PLBC. Cows fed NG and supplemented with PLBC produced 3.5 % less milk than cows supplemented with SFBC. However, milk production profit was 22 % higher for cows supplemented with PLBC than for cows supplemented with SFBC. Milk production profit in rural areas was 68 % lower than in areas near urban centres. Use of PLBC would therefore lower cost of milk production in dairy cows fed NG based diets.


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Page publiée le 25 janvier 2018