No abstract

In two similar experiments, Lablab purpureus was sown at dierent dates in July and August to evaluate the eects of sowing date on the yield and nutritive value of the plant and shed leaves. On each occasion, an interim harvest was performed on half of the plants sown at each date and the regrowth recorded. The interim harvest reduced the total yield, and in particular that of shed leaves. In one of the two experiments, late sowing resulted in a considerable reduction in yield, increased crude protein and reduced modi®ed acid-detergent ®bre concentrations. Ash concentrations were higher in plants sown later and their shed leaves. Sodium concentrations were inadequate for ruminants and, like phosphorus concentrations, tended to decrease with later sowing. However, both calcium and magnesium concentrations increased with later sowing and were sucient for ruminant production. Potassium concentrations were high and were little aected by sowing date. It is concluded that both an interim harvest and late sowing are disadvantageous when lablab is grown for ruminant livestock, the former because of yield reduction and the latter because of yield reduction, increases in ash concentration and reductions in sodium and phosphorus concentrations.

Baseline management practices and productivity of captive greater cane rats were studied between February and July 1992 using questionnaires with 33 practising and former farmers in 16 villages in three regions in southern Ghana. The colony sizes were relatively small, ranging between 1 and 96, with nearly a 100% farmer drop-out rate. The mean litter size of the greater cane rats in this study was 4.8+/-0.13, with the young being weaned at 8.8 weeks old. Although nearly all the farmers interviewed (90.9%) had long-term commercial intentions, a number of problems militating against their objectives were encountered. These included lack of technical support on proper management practices for efficient production, housing design, dry season feeding, sex determination and the acquisition of foundation stock. In conclusion, these studies have shown the generally poor state of the greater cane rat industry in Ghana, which requires research into almost all aspects of the productivity of this animal under captive breeding.

In two years the growth and composition of mixtures of sorghum with Lablab purpureus as strips, paired rows and alternate rows were compared with those of sorghum and lablab monocrops. In the first year, when sowing did not occur until 7 August, the sorghum yields were low in the monocrop and even less in the mixed crops. Lablab yield was also reduced in mixtures compared with the monocrop, but total forage yield was greater for the mixed crops compared with sorghum alone. Of the mixed cropping systems, a reduction in the yield of lablab plants and in the phosphorus and potassium content of shed lablab leaves in paired rows suggested that there was more competition for nutrients between lablab plants grown in this treatment. In the second year, earlier sowing increased sorghum growth at the expense of lablab yield in the mixed cropping systems, with the result that total forage yield was not increased when sorghum was intercropped with lablab. However, the crude protein content of sorghum stems and leaf yield were increased in mixed crops, particularly in paired and alternate rows rather than strips, demonstrating that close configuration of the legume and cereal are necessary for the cereal to obtain most benefit from nitrogen fixed by the legume. It is concluded that, when conditions are favourable for rapid sorghum and lablab growth, the sorghum will benefit more when it is grown in paired rows with lablab rather than in strips. However, the close spacing normally adopted for paired rows may encourage competition between lablab plants and increase the requirements for phosphorus and potassium fertilizer.

Lablab purpureus was grown in two ®eld experiments in consecutive years to evaluate the eects of the timing of an interim harvest on the yield and nutritive value of the harvested material and the subsequent regrowth, which was determined from the second and ®nal harvest. Delaying the ®rst harvest to 50±70 days post-sowing increased the total (®rst plus second harvests) dry matter (DM) yield, with a greater ®rst harvest and reduced second harvest DM yield. The delay also reduced the crude protein concentration of the ®rst harvest and tended to increase its modi®ed aciddetergent (MAD) ®bre concentrations. The delay increased the crude protein concentration and decreased the MAD ®bre concentration of the second harvest. The total crude protein yield of both harvests increased with late interim harvesting. The ®rst harvest plant calcium concentration increased and phosphorus concentration decreased with a delay in the interim harvest. It is concluded that, in the dicult growing conditions of the Sahelian zone of sub-Saharan Africa, delaying the interim harvest of Lablab purpureus until 50±70 days post-sowing will have bene®cial eects on total dry matter and crude protein yields.