**3.2 Reproductive performance**

Reproduction is the major determinant of profitability in a cattle enterprise. A cow needs to be re-bred in 80 to 85 days post calving to sustain a 365-day calving interval. Percentage of body fats in cows is directly linked to poor reproductive performance. Inadequate nutrition causes poor reproductive performance and researchers have discovered that for proper functioning of the reproductive system, a certain level of body fat must be attained. It becomes easier to develop more cost-effective a nutrition program if all of the farm's cows can be managed similarly. This is certainly relevant when a farm's entire herd of cows is maintained as a single herd, which is common in small production units [29]. All cows suffer from poor body condition at vital times due to year-round calving. Reduced income per cow, prolonged time before rebreeding, poorly conditioned calves at birth, low quality and scarce colostrum, decreased milk production, a high rate of dystocia, and lower calf weaning weights are all possible consequences. A longer interval between rebreeding and weaning will result in a younger, smaller calf at weaning the following year, resulting in lower profits if the animal is sold at weaning. Calves that were weak at birth may find it difficult to get reasonable amount of colostrums. This may give rise to high susceptibility to diseases, light weaning weights, decreased feedlot performance and poor carcass traits. As reported by researchers, there is clear evidence cows with a moderate body condition had a shorter delay between calving and initial estrus than cows with a bad body condition [29].

According to [44], 6–10 calving per cow per reproductive cycle is allowed by about 90.90% of pastoralists in Nigeria, while about 9.10% usually allow about 11–15 calving per cow. Therefore, majority of the aged cows are often slaughtered for sale in most abattoirs [48]. However, cattle production and breeding efficiency on Northern Nigerian grazing rangelands is low, especially during the dry season [49]. Cows, for example, have a two-year age at first calving and a two-year calving interval [50, 51], steers achieve slaughter weight between 24 and 30 months of age [52], and off-take rates range from 2 to 10% per year [49]. The median age at first calving for the reproduction was 4.75 years, according to [34]. The findings corroborated previous data on Bunaji cattle herds gathered from the Jos Plateau [52]. However, the result was higher than 37-month reported at the National Veterinary Research Institute, Vom, a government farm [53]. The difference is due primarily to the dry season's low amount and quality of feed on grazing fields [50, 54]. In such circumstances, providing feed supplements to boost cow output may be recommended. However, before any nutritional modifications are proposed, it's critical to figure out which nutrients are restricting cattle productivity in a certain zone [55]. Akpa et al. [34] equally reported a before breeding, the average age was 4.05 years for bulls in the pastoral cattle herds. This may be probably occasioned by poor nutrition acting together with other environmental stressors. Ndlovu et al. [56] made findings that the age at which young bulls reach puberty is affected by nutrition and feed intake. However, [47] suggested that where controlled breeding is being practiced, young bulls of about 15 months of age should not run with the cows in the pasture. Some researchers have used standard technical coefficients to compare results obtained in research institutions such as the National Animal Production Research Institute in Zaria or the National Veterinary Research Institute in Vom, as well as those in Nigeria's traditional model [44]. Data were collected on reproductive performance and milk to butter ratio. The results, *inter alia* showed that the proportion of milk to butter was 1 liter to 100 grams. When compared to the data above, it can be seen that the calving cycle in Nigeria ranges from 29 to 43 months. The average age at first calving is 30 to 42 months, with a productive life of between 9 and 14 years [44].
