Enhancement of smallholder dairy production under tropical conditions through supplementation to optimise roughage intake, digestibility and microbial protein synthesis
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Date
2001
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The Royal Veterinary and Agricultural University
Abstract
This thesis addresses the nutritional related constraints facing the smallholder diary sector in Tanzania in general and Morogoro in particular. Smallholder dairy production practices and feeds were assessed though a structured survey carried out between January and March 1999 (Paper I). Monthly collection of forages used by farmers was done over a one-year period. The forage samples were analysed for chemical composition and in vitro organic matter digestibility to determine the annual variations in the nutritional quality. It was found that smallholder producers were playing a key role in the provision
of dairy products that are in high demand in urban areas like Morogoro, in Tanzania. One of the limiting factors to enhanced productivity was the fall in milk yield (more than 40%) during die dry season. Forage analyses revealed that there was a fall in nitrogen and Metabolizable energy contents and organic matter digestibility with advancing dry season.
The impact of low nitrogen in the basal feeds on animal performance was further
investigated in an on station experiment set to determine the effects of nitrogen
supplementation on feed intake, digestibility and rumen fermentation in animals fed poor quality forage (Paper II). In a 5x5 Latin square design, five ruminally fistulated heifers were assigned to either low quality hay only or supplemented with either low or high level of true protein (soyabean cake) or non-protein nitrogen (urea) (Paper II). At each level of supplementation, both urea and soyabean cake were iso-nitrogenous. Both
soyabean cake and urea supplementation of poor quality forages led to significant
improvement in the dry matter (DM), organic matter (OM) and plant fibre digestibility and microbial protein synthesis. Soyabean cake showed marginally higher (not significant) responses in most parameters at all levels compared to urea except for digestible NDF digestibility where the high level of urea supplementation showed a
higher (not significant) value compared to soyabean cake. The superiority of soyabean cake may have been due to the extra DM, energy, pre-formed amino acids, minerals and extra amino acids arising from by-pass protein invariably associated with this supplement. Calculated price of supplemental protein from soyabean cake was about 3.3
Tsh compared to 0.1 Tshs per gram CP urea (see Table 1). Therefore, as far as
fermentation of plant fibre was concerned, urea was equally good and a better option
given the high prices of true protein sources like soyabean cake.
One other interesting observation during the survey (Paper I) was the attempts
by farmers to offer supplements to their cows especially the lactating ones. Surprisingly, most of the supplements used were energy rich (maize bran, molasses and cassava flour)ii while protein rich supplements were rarely used. A second on station experiment was set to investigate the effects of the commonly used supplements and a feed additive called “Magadi” on the intake and utilisation of poor quality roughage (Paper III). The experimental set up was a 5x5 Latin square design involving 5 ruminally fistulated heifers, 5 treatments and 5 periods of 28 days each. The treatments were poor quality hay plus
maize bran (2.7kg DM) (control), or the control plus starch (0.9 kg DM cassava flour), sugars (1.3kg DM molasses) or “Magadi” (0.3kg). The fifth treatment was the poor quality hay supplemented with concentrate mixture (2.8kg DM) containing energy (68% maize bran) and protein (31% sunflower cake) and 1% mineral commercial mineral powder instead of the maize bran used in the control.
Inclusion of “Magadi” or molasses or cassava flour in animals receiving equal
amounts of maize bran produced variable results. Sugars increased OM intake and digestibility with little change in NDF digestibility compared to the control. Starch increased DM and OM intake and digestibility but reduced NDF digestibility due to high passage rate of NDF. “Magadi” did not improve DM intake but NDF digestibility and microbial protein synthesis were higher compared to supplementation with maize bran alone. There was also a higher in situ degradation of hay DM from dacron bags soaked in “Magadi” for 24 hours prior incubation in the rumen of standard cows compared to those soaked in tap water. This suggested that better response might be obtained through
treatment of poor quality hay with “Magadi” than direct feeding. The supplement that contained a mixture of maize bran and sunflower cake fed to about 35% of total DM intake improved intake and digestibility of poor quality roughage compared to supplementing with plain maize bran as is the common practice with smallholder farmers
in Morogoro. It was interesting to investigate whether the energy-protein concentrate mixture could be used by smallholder farmers in Morogoro as dry season supplement in order to arrest or reduce the fall in productivity during this season when the basal feeds are deficient in nitrogen and to some degree, energy. The major ingredients for making such
a mixture (maize bran and sunflower cake) are easily available and reasonably cheap in Morogoro. Farmers were trained on how to compound such supplement on their own at farm level. The effect of feeding the concentrate mixture or maize bran alone as commonly done by most farmers was assessed through an on farm trial involving a total of 18 farms and 47 milking cows (Paper IV) in urban and peri-urban areas of Morogoro.
Description
PhD Thesis
Keywords
Smallholder Dairy Production, Tropical Conditions, Supplementation, Digestibility, Microbial protein synthesis