The potential of leucaena pallida and acacia angustissima fodder in improving the productivity of dairy cattle in Tabora region

Abstract

Four experiments were carried out to evaluate the feeding value of L. pallida and A. angustissima and determine how these fodder materials could be managed and used for sustained dairy production in the farming system in Tabora Region, Western Tanzania. The first experiment involved assessing the yield and nutritive value of£. pallida and A. angustissima as related to cutting management. In experiment 2, the effect of post-harvesting treatment methods on the level of secondary compounds were evaluated. Experiment 3 was carried out to investigate the effect of supplementing L. pallida and A. angustissima leaf meals to lactating dairy cows fed grass hay on milk yield, quality and financial return of the rations. Experiment 4 was undertaken to determine digestibility and nitrogen balance in dairy cows fed grass hay supplemented with dried leaf meals from L. pallida and A. angustissima. Results showed that the 3-months cutting interval had the highest fodder yield (3.44 and 5.41 tDM/ha for L. pallida and A. angustissima, respectively) while 1-month cutting regime had the lowest fodder yield (2.8 and 3.4 tDM/ha for L. pallida and A. angustissima, respectively). Nitrogen and mineral contents varied significantly (P < 0.05) between cuttings and edible fractions, which ranged from 27.1 to 47.7 for nitrogen, 2.37 to 8.49 for calcium, 1.40 to 4.90 for phosphorus and 11.6 to 23.1g/kg DM for potassium. Condensed tannins (CT) in the edible fractions ranged from 8 to 16 and 17 to 33mg/g DM for A. angustissima (AA) and L. pallida (LP), respectively. Mimosine content ranged from 26.8 to 63mg/g DM in edible fractions of L. pallida. In both species, In-sacco DM and N degradability at 48 hours of incubation were significantly (P < 0.05) higher in 1-month cuttings than in the other cuttings and ranged from 442 to 591g/kg for DM and 503 to 618g/kg DM for nitrogen. Soaking in water, sun drying, wilting and drying under shade of the edible fractions reduced 37 to 50%, 22 to 40%, 12 to 18% and less than 10% of CT content, while mimosine content was reduced by 74 to 91%, 41 to 55%, 20 to 40% and 22 to 26%, respectively. Milk yield was highest for cows supplemented with cotton seed cake (CSC) (9.94 kg/day) and lowest for cows supplemented with LP (7.78 kg/day). Supplementing mixture of the two browse leaf meals gave the highest net return (104.20 Tshs/litre) while CSC recorded the lowest net returns (66.60 Tshs/litre). Apparent DM and N digestibility were higher for cows supplemented with CSC (585g/kg and 931g/kg for DM and N, respectively) and lowest for cow supplemented with LP (466g/kg and 603g/kg DM for DM and N, respectively). The N absorbed was more efficiently retained (P < 0.05) with cows supplemented with CSC (21.8 g/day) and poorly retained with cows supplemented with AA (4.24 g/day). These results indicated that optimal yield and quality of edible fodder materials of the two browse species could be obtained at 2-months cutting interval. Soaking in water and/or drying in the sun could reduce tannins and mimosine content in the edible fractions to an acceptable level before feeding. The two browse species had high CP and mineral contents and were more economical than cotton seed cake as protein supplement. Agronomic strategies to maximize fodder production during the dry season should be given attention. Studies to determine the effect of tannins and other related polyphenolic compounds on protein availability and utilization by ruminant animals should be carried out.