Carcass and meat quality attributes of Malawi Zebu steers fed Vachellia polyacantha leaves or Adansonia digitata seed as alternative protein sources to Glycine max

Abstract

To enhance smallholder beef farmers’ capacity to cope with animal feed shortages, especially dietary protein induced by climate change, it is important to evaluate the feeding value of low-cost protein sources naturally available in the environment. The aim of the study was to evaluate carcass and meat quality of Malawi Zebu steers fed diets containing Adansonia digitata (baobab) seed meal or Vachellia polyacantha (white thorn tree) leaf meal as alternative protein sources to Glycine max (soybean) under feedlot conditions. Thirty Malawi Zebu steers (181 ± 21.4 kg body weight; 29 months old) were individually fed forage-based diets made up of rangeland hay and maize bran, with either baobab seed meal, Vachellia leaf meal or soybean meal as a protein source for 120 days. At the end of the feeding trial, animals were slaughtered and the longissimus thoracis et lumborum muscle sampled for meat quality analyses. Steers fed soybean and baobab diets had higher subcutaneous fat thickness, carcass weights than those fed the Vachellia diet. Meat from steers fed the Vachellia and baobab diets had higher ultimate pH and water-holding capacity, and lower drip and cooking losses than meat from steers fed the soybean diet. Feeding baobab and Vachellia diets produced beef with lower lightness (L*) values than the soybean diet, characteristic of dark, firm and dry (DFD) beef. Steers fed the baobab diet had the highest gross profits followed by those fed the Vachellia and soybean diets, respectively. Overall, feeding the baobab and Vachellia diets improved gross profit but produced DFD beef compared to the soybean diet.

Keywords: beef cattle, baobab seed, soybean meal, smallholder production