Supplementation of Napier With Legume And Feed Additives For Sustainable Dairy Production In Smallholder Farms In Rwanda

Abstract

In Rwanda, dairy farmers are still using low quantity forage and mainly Napier grass (Pennisetum purpureum), resulting in reduced milk production and increased enteric methane emission per unit of product. Improving cattle productivity and efficiency is therefore a key to improving productivity and minimizing methane emissions through good farm management practices, providing good quality feeds, or the use of feed additives. The government promoted forage legumes including Calliandra calothyrsus and Clitoria ternatea for livestock nutritional enhancement. Nevertheless, these feed additives are not widely spread to farming communities in Rwanda. However, the effectiveness of supplementation of Napier with legumes and feed additives is not well documented. This study aimed at improving milk production and methane gas emission reduction in smallholder farms by assessing the existing potential feeds and use of Calliandra, Clitoria, Polyethylene glycol, and garlic powder as supplements to Napier. The first three objectives were to assess the existing and potential feed resources for improving livestock productivity in the three Agro-ecological zones of the Eastern Province of Rwanda, determine the use of feedstuffs among smallholder dairy farmers, and determine their effect on milk production and enteric methane emissions. The three objectives were achieved through a survey on the production system, feed monitoring, proximate, and milk analysis, while Tier II approach that considers feed characteristics was used for methane estimation. The fourth and fifth objectives assessed the feed utilisation potential of Calliandra, Polyethylene glycol, and garlic powder through in vitro gas production. Descriptive statistics were used for the data of the first objective while data from the other objectives were subjected to the analysis of variance. Twenty-two types of feeds were identified across the three zones, Napier was widely spread across the zones throughout the year. The mean daily milk production of lactating cows was 5.6 L with a lower value (P<0.05) during the long dry season (4.76 L). The mean emission factor was 57.96 Kg of CH4/year with significant (P<0.05) variations. The zone with a high protein feed supply had the lowest methane emission per Kg of milk production. The total volatile fatty acid production was affected by the addition of Clitoria and Calliandra. The inclusion of Calliandra reduced the in vitro methane emission by 4.4% and increased the total volatile fatty acids by 5% compared to the basal substrate alone. Garlic at 2% level, reduced in vitro methane production. It was concluded that Clitoria and Calliandra as well as other legumes forages should be evaluated and introduced to smallholder dairy farmers for increased milk production and reduced methane emissions. The efficacy of feed additives was low. It is recommended that in vivo experiments be conducted to evaluate the performance of legumes, Polyethylene glycol, and garlic supplemented to Napier grass as a basal diet.