EFFECTS OF FORMS OF MAIZE (Zea mays L.) GRAIN ON BIOMASS YIELD, NUTRITIVE VALUE, MILK PRODUCTION AND QUALITY OF DAIRY COWS

Abstract

A survey and other three interrelated trials were conducted on the objective of selecting the best maize form that would substitute brewery grain in crossbred (Fogera and Holstein Friesian) dairy cows ration. In the survey (paper I) a cross-sectional single visit multi-purpose design was used to assess farmers’ perception, and available practices for hydroponic fodder production. In paper II and III, a 4 x 3 factorial experiment (four maize varieties with three seed rates) in a Complete Randomized Block Design was used to evaluate the effect of varieties (BH540,BH660, BH661,MVFG) and seed rate (5.6, 7.6 and 9.6kg m-2) on hydroponic maize fodder biomass yield, chemical composition, and water use efficiency; in paper IV, the three forms (i.e. the grain, malt and hydroponic fodder) of the selected variety of maize and seed rate were compared for their in vitro Digestibility, in Sacco degradability and enrgy contents in a completely randomized design; and in paper V, a double 5 x 5 crossover design (five treatment diets and five experimental periods) were used to evaluate the effect of different forms of maize (the grain, malt and hydroponic fodder) versus brewery grain supplementation on yield, composition and economy of milk production. The survey was conducted in Gondar, Mekele, and Tachi-Gayint whereas the experiments were at University of Gondar-Atse Tewodros campus. Results of the survey (Paper I) showed that feed, milk market, space, and artificial insemination service unreliability were the top four problems of dairy farming. Among coping strategies to feed scarcity, purchasing additional feed was the first measure employed. Out of the total 436 dairy cattle owners in the study area, 30 (6.9%) (P<0.01) were involved in hydroponic fodder production (HpFP). A greater proportion (56.7%) of dairy cattle owners having experience of using hydroponic fodder (HpF) witnessed that HpF improved milk production, calf growth, and animal’s body condition. In spite of the fact that the majority of the required facilities (75.7) for HpFP exist in the study area, seed cost and information on the effect of the fodder on productivity and health of animals limited its wider adoption. The majority of dairy cattle holders in peri-urban consider HpF as a good opportunity and ready to implement if they are certain that its production is cost-effective, increases milk production, and does not cause any health hazard on animals. The results of the second experiment (Paper II and III) showed that BH661 produced higher (P<0.01) HpF (6.63 kg) DM m-2 and it is also the least expensive variety. Among seed rates, the high seed rate has a higher (P<0.01) DM fodder yield per square meter. However, it is exceeded by the medium seed xvii rate in DM fodder conversion efficiency. Medium seed rate has lower (p<0.05) cost of production per kg DM fodder when compared with the high seed rate. The results of the third experiment (Paper IV) have shown that the DM (90.20%) and non-fibrous carbohydrate (NFC) (78.00%) content of maize grain decreased to 51.79 and 58.12, respectively as a result of malting and to 18.39 and 46.39, respectively as a result of sprouting. Malting and sprouting increased the CP content of maize grain from 7.97 to 9.53 and 10.90 percent, respectively. Malting increased (P<0.01), but HpFP decreased (P<0.05) the IVDMD and IVOMD and energy content of maize grain. Malting and sprouting increased (P<0.01) the rapidly and effectively degradable maize DM. Potentially degradable DM of malt and grain was similar (99.50 vs 99.68%) but higher (P<0.01) than the sprout (91.63%). Malting and sprouting increased (P<0.01) the rapidly and effectively degradable CP of the maize grain, however, decreased (P<0.01) slowly degradable CP. The results of the fourth experiment (Paper V) have shown that cows supplemented with maize hydroponic fodder (MHpF) produced more (P<0.05) milk than those supplemented with MG and control diet. There were no significant differences in milk sensory attributes and milk composition except milk protein which was higher in MHpF, maize malt (MM) and brewery dried grain (BDG) supplementation. Under both scenarios, BDG has higher (P<0.05) net benefit followed in order by miaze malt (MM). There was no difference (P>0.05) between MHpF and maize grain (MG) supplementation in net benefit. The marginal rate of return (MRR) value of MHpF for commercial farming (0.99) was almost at a breakeven value indicating if other advantages is sought; hydroponic fodder can be used in commercial farms with no loss of profit. Therefore, it is concluded that hydroponic maize fodder production can be profitably run in smallholder dairy farming with family labor. Using brewery grain, when available, with adequate energy supplement is more profitable. When the supply of brewery grain is scarce, the use of MM as a supplement would be preferred than MHpF and MG. Since the net benefit from grain and hydroponic fodder supplementation was similar, it seems that sprouting has no economic advantage. Future research areas should focus on maximizing hydroponic fodder productivity, minimizing hydroponic fodder production cost and usefulness of MHpF in improving animal disease such as bovine calf blindness.