Effect of replacement of concentrate mix by wilted sesbania ( Sesbania sesban) forage on diet digestibility, rumen fermentation and milk production in Friesian X Zebu (Boran) crossbred cows fed low quality native hay

Abstract

Sesbania ( Sesbania sesban) forage, including leaves and edible stems (stem diameter 2–3 mm) in the ratio 1:3, as a replacement for concentrate supplement in dairy cattle feeding was studied in a 4 × 4 Latin square design experiment with four rumen-cannulated lactating crossbred cows. All the animals were fed a basal diet of low quality native hay, mineral lick and water ad libitum. In Diet 0, the basal diet was supplemented with 4.5 kg air dry commercial concentrate based on noug ( Guizotia abyssinica) cake and wheat middling. In Diets 33, 66 and 100, respectively, one-third, two-thirds and all of the concentrate was replaced with sesbania forage. Nitrogen content of sesbania forage was clearly lower than that of concentrate, but rumen degradation constants indicated that for both the concentrate and the wilted sesbania forage, a major part of the nitrogen was instantly degraded. Increasing sesbania forage on offer in the diet caused a slight, but statistically significant (P < 0.01) linear decline in total feed intake, because all sesbania was not consumed. The simultaneous very clear linear decrease in daily milk yield was also statistically significant ( P < 0.01). Dietary crude protein digestibility decreased ( P < 0.05) with increasing sesbania supplementation, because the proportion of easily or potentially degradable protein was smaller in sesbania than in the concentrate. The supply of metabolisable energy, calculated based on digestible organic matter, was always sufficient to maintain the highest milk production level of Diet 0, but insufficient digestible crude protein limited the milk yield on sesbania diets. To assess nutritionally harmful effects of sesbania forage, long-term trials with more animals are needed.