Twenty-four weaner pigs were used in a study to evaluate the response of weaner and grower pigs to diets containing graded levels of toasted soybean hull (SBH).In experiment 1(growing phase), twenty-four male hybrid (large white x landrace) weaner pigs, about 6 weeks old, weighing 5.92-6.85kg were randomly divided into four groups of six pigs each using a completely randomized design (CRD). Each group was randomly assigned to one of the four diets (1, 2, 3 and 4) containing 0% (control), 10, 15 and 20% SBH for 56 days. Each treatment was replicated 3 times with 2 pigs per replicate placed on a concrete-floored pen. The diets were formulated to be isocaloric and isonitrogenous supplying 2800kcal ME/kg and 18% crude protein. In experiment 2 (finishing phase), twenty-four male hybrid (large white x landrace) grower pigs, about 14 weeks old, weighing 9.12-9.90kg were randomly divided into four groups of six pigs each using a completely randomized design (CRD). Each group was randomly assigned to one of the four diets (1, 2, 3 and 4) containing 0% (control), 10, 20 and 30% SBH for 56 days. Each treatment was replicated 3 times with 2 pigs per replicate placed on a concrete-floored pen. The diets were formulated to be isocaloric and isonitrogenous supplying 2900kcal ME/kg and 16% crude protein. Daily feed intake, body weight gain, feed conversion ratio, protein efficiency ratio and feed cost per kg weight gain were determined. At the end of each experiment, blood samples were collected from two pigs per treatment for haematological evaluation. Two pigs per treatment were also slaughtered for carcass evaluation at the end of the finishing experiment. In experiment 1, results showed that pigs fed the 10% SBH diet had higher(P<0.05) average final body weight, average weight gain and better efficiency of feed conversion than those fed 20% SBH diet. Increasing levels of SBH in the diets had no significant effect (P>0.05) on the PER values. Differences between the treatments in total digestible nutrients (TDN) were significant (P<0.05). Feed cost per kg weight gain was reduced at the 10% SBH inclusion level as compared to other SBH diets. Dietary treatments did not have adverse effect on the haematology of growing pigs. The overall performance of pigs fed the soybean hull based diets was not inferior to that of pigs fed the control diet (0% SBH). In experiment 2, the 20% and 30% SBH diets supported superior final body weight gain and growth rate, better feed conversion ratio, higher protein efficiency ratio, average daily protein intake and feed intake than the control diets(P<0.05). Inclusion of SBH in the diets reduced significantly (P<0.05) the cost of feed per kg weight gain, especially at the 30% SBH inclusion level. Pigs fed the control diets had comparable packed cell volume (PCV), haemoglobin concentration (Hb), red blood cell counts (RBC) ,white blood cell counts (WBC), mean corpuscular haemoglobin concentration (MCHC), mean corpuscular haemoglobin (MCH) and mean corpuscular volume (MCV) values with the groups on SBH diets. While dietary levels of SBH did not exert significant(P>0.05) influence on body length, height at withers, lung weight, liver weight, spleen and pancreas weight; the heart girth circumference, heart weight, kidney weight, live body weight, and dressed carcass weight were all significantly (P<0.05) affected by the dietary levels of SBH. The dressing percentage, relative weights of lungs, liver and spleen were also influenced significantly (P<0.05) by the dietary levels of SBH, while the relative weights of heart and kidney were not significantly (P>0.05) affected. It was concluded that toasted soybean hull can be included in the diet of weaner pigs at 20% level and in the diet of grower pigs at 30% level without adverse effects on the performance, haematological values, carcass and organ weights of the animals.
The scarcity of conventional feeds has hindered the growth of the livestock industry in Nigeria. The food deficit problem is indeed more serious with protein supply when compared with the availability of calories. Shortage of protein, particularly those of animal origin is prevalent in most parts of Africa where it is estimated that on the average 10g of animal protein is consumed per day compared to a recommended daily intake of 35g (ILCA, 1980, FAO, 2017). According to Obioha (2012) and Ogini (2011), the level of consumption of meat and animal protein in Nigeria is estimated at about 8g per caput per day, about 20g less than the minimum requirement by the National Research Council of the United States of America. Therefore, there is the need, to increase the production of such domestic animals as pigs and poultry which are conventional sources of animal protein. Pig production in particular represents one of the fastest ways of increasing animal protein, since pigs grow at a faster rate and are highly more prolific than cattle, sheep and goats. In growth rate pig is only surpassed by broilers (Holness, 2015). Apart from their high rate of reproduction, pigs and poultry are characterized by the best efficiency of nutrient transformation into high quality animal protein (Smith, 2011; Holness, 2015).
Apart from the poultry industry, pig farming has the highest quick returns on investment. The high cost of the conventional feedstuff most especially the protein supplement, necessitated the quest for locally available alternatives that can substitute for the conventional feedstuffs economically by reducing feeding cost, thereby making the pig enterprise a more profitable one (EL-Sabben et al., 1970; Fontenot,2011). The alternative cheap and available feedstuff to be considered in this study is Soy bean hull. Soybean hulls referred to as soy hull, soybean mill-run or soybean flakes are by-products of soybean milling industry which do not attract competition between man and animals. Soybean hull is readily available when compared to other alternative sources of feed ingredient. Soybean hull has estimated feeding value of 74-80% of that of maize when included in moderate to high quantity in maize based diets (Esonu, 2014). It contains high level of potentially digestible fibre and can replace some or all grains in the diets of ruminants (Van Soest, 2015). Soybean hull contains 22.75% crude protein, 18.15% crude fibre, 14.60% ether extract, 8.0% ash and 20.90% nitrogen-free extract (Preston, 2015; Esonu et al., 2017; Esonu, 2014). However, the utilization of soybean hull in the feeding of monogastric animals is limited by the presence of such anti-nutritional factors as trypsin, chymotrypsin and amylase inhibitors, lipoxygenase, hemagglutinin, phytic acid and the toxin, soyin and must be heat-treated to destroy them (Ensminger et al., 2016; Enwere, 2014; Holness, 2015). Besides anti-nutritional factors, another limitation is its high fibre content. Pigs cannot fully utilize high fibre diets because they lack the digestive framework that can elaborately digest large amount of fibre. Although there is scarcity of information on the utilization of soybean hull, soybean hull has an acceptable proximate composition and occurs in relative abundance in all seasons, it should be exploited and evaluated for inclusion in livestock diets.
This study is therefore; aimed at evaluating the growth performance, cost implication, blood parameters and carcass characteristics of weaner and grower pigs fed graded levels of soybean hull-based diets. The major objectives of the study are as follows:
i. To determine the effects of graded levels of soybean hull on performance of weaner and grower pigs.
ii. To determine the effects of graded levels of soybean hull on haematology, carcass and organ weights of grower pigs.
iii. To determine the optimum inclusion level of soybean hull in the diet of weaner and grower pigs.
iv. To determine the cost implication of feeding graded levels of soybean hull to weaner and grower pigs.