C. Mutisi

The Nutritive Value, Intake, Digestibility and Nitrogen Balance of Farm-grown and Prepared Sunflower-based Dairy Calf Meals

The dry matter intake (DMI), digestibility and nitrogen balance of three sunflower-based farm-grown calf meals with different roughage sources (maize stover, MSM; groundnut tops, GTM; and veld hay, VHM) and a commercial calf starter meal (control; CSM) were studied for 47 days (26 days pre- and 21 days post-weaning) in calves. The DMI was lower (but p>0.05) with CSM (0.369 kg/day) than with the farm-grown meals (mean 0.559 kg/day), and the daily weight gain (kg/day) did not differ significantly (p>0.05) between CSM (0.107), GTM (0.053), MSM (0.157) and VHM (0.217). Dry matter, organic matter and protein digestibility were higher (p<0.07) on the CSM than on the GTM treatment. Nitrogen retention was least (p<0.05) in calves fed GTM (3.0 g N/day) compared to those fed MSM (10.4), VHM (5.0) or CSM (3.9). These results indicate that farm-grown and prepared sunflower-based meals are suitable for feeding young calves.

The Concentration of Faecal Progestins during the Oestrous Cycle in Nkone Cows and the Effect of Duration of Storage of Faecal Samples at Room Temperature on Faecal Progestin Levels

The objectives of this study were to determine whether ovarian function in Nkone cows could be monitored by measuring progestin concentrations in faeces and to assess the effect of duration of storage at room temperature on faecal progestin concentrations. Faecal and blood samples were obtained once a day for 26 days from 21 Nkone cows whose oestrous cycles had been synchronized. Faecal samples from each cow were divided into five portions that were kept at room temperature for 0, 6, 12, 24 and 48 h, respectively, and then frozen. After centrifuging the blood to recover plasma and extracting steroids from the faeces, analysis of progesterone (P4) was carried out using solid-phase radioimmunoassay. The faecal progestin and plasma progesterone profiles corresponded well and were positively correlated (r = 0.70, p>0.01). Faecal progestin concentrations decreased with increasing duration of storage at room temperature during both the follicular and luteal phases (p>0.01). In both cases, the decline in faecal progestin concentrations followed an exponential pattern. The progestin concentrations in faeces after 48 h of storage at room temperature were higher (p>0.05) during the peak luteal phase than in the follicular phase.