RT Dissertation/Thesis
T1 Effects of ensiling conditions on the nutritional quality of forage legumes and their impacts on rumen fermentation and nutrient utilization by cattle
A1 Aloba,Temitope Alex
WP 2023/08/16
AB Silage produced from forage legumes can contribute to the limiting protein supply of ruminants diets in the tropics, and reduced dependence on imported and high-carbon footprint feeds. However, the successes recorded with temperate forage legume silage feeding in ruminants have not been achieved in the tropics. Thus, the effects of silage feeding on ruminants’ performance cannot be isolated from the processes that occur during ensiling. Since controllable and uncontrollable factors govern silage quality, it is imperative to understand the processes that occur during ensiling tropical forage legumes under different conditions to widen knowledge. Therefore, the aim was to determine the effect of ensiling conditions on forage legume nutritional quality, their ruminal and post-ruminal fate, and their potential impact on nutrient utilization by cattle in the tropics. 
A silage study was conducted to evaluate the effects of ensiling length and storage temperature on the nutritive value and fibre-bound protein of three tropical forage legumes ensiled alone or combined with sorghum. The three forage legumes included soybean (Glycine max), lablab (Lablab purpureus) and jack bean (Cannavalia ensiformis). Silages from each legume were made individually or combined with sorghum (Sorghum bicolor) and stored outdoors or indoors for 30, 75, and 180 days. The results showed that the proportion of soluble nutrients preserved in most silage until 75 d of ensiling declined considerably, thereby increasing dry matter (DM) and crude protein (CP) losses, fibre concentration and reducing digestibility afterwards. Besides, storage temperature affected the fermentation and fibre-bound protein characteristics with higher variation in legume silages’ fibre-bound protein than the sorghum-legume silages.
Silages of sorghum and soybean were selected from the first study to compose low and high CP diets with additional ingredients, and the effects of ensiling length, storage temperature, and its interaction with CP levels on in vitro rumen fermentation and post-ruminal digestibility were assessed. Dietary treatments were incubated in duplicate for 8 and 24 h in three runs using the ANKOM RF technique to study rumen fermentation. Post-ruminal digestibility was determined using the pepsin and pancreatic solubility procedure. The results showed that gas production (GP) and ammonia-nitrogen in the rumen inoculum increased quadratically with the ensiling length, with the highest GP and ammonia-nitrogen at 75 d of ensiling, irrespective of incubation times. The GP was higher in diets with low than high CP concentrations, while it was the opposite for ammonia-nitrogen. An interaction between ensiling length and storage temperature effect was found for the apparent CP intestinal digestibility. Overall, ensiling beyond 75 d reduces CP digestibility to the extent that it cannot be recovered by supplying additional CP.
In the third study, the effects of CP levels on nutrient intake, digestibility, nitrogen metabolism and performance of growing steers fed corn or corn-soybean silage were investigated. Sixteen growing steers were fed with rations based on corn or corn-soybean silage at high or low CP levels in a 4 × 3 incomplete Latin square design comprising 17 d periods, each with 12 d of adaptation to dietary treatments and 5 d of sampling. While the effect of silages and CP levels were not found for nutrient intake, the apparent total tract digestibility of nutrients was reduced for low than high CP in both silages, with greater differences between the CP levels in corn than corn-soybean silage. The average daily gain and feed efficiency were greater in low than high CP of corn silage, but no differences between CP levels were found in corn-soybean silage. In general, corn silage with low CP concentration but with a high metabolizable energy supply supposedly improved nitrogen use efficiency with a higher yield of microbial protein and average daily gain than other diets.
Conclusively, the results of the current thesis showed that ensiling forage legumes individually or in combination with cereal crops beyond 75 d at high temperatures of the tropics leads to a decline in the nutritional quality of legume silage and CP intestinal digestibility even with additional CP sources. Furthermore, prolonged ensiling of combined legume and cereal crops reduces nutrient availability for cattle performance.

K1 Silage
PP Hohenheim
PB Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim
UL http://opus.uni-hohenheim.de/volltexte/2023/2189