Meat is becoming a highly scarce commodity especially at a time when staples like garri, cowpea and rice can not be reached by many consumers as a result of the global food crisis which is currently plaguing the country as well as many other countries in the world.
Due to the expensive nature of poultry meat and egg, beef, mutton, pork, chevron etc, people now have resorted to frozen fish consumption which was ignored years ago. Shortage of protein particularly those of animal origin, is prevalent, not only in Nigeria but also in most parts of Africa, where it is estimated that on the average, 10g of animal protein is consumed per day per person, compared to a recommended daily intake of 35g (ILCA, 1980).The level of consumption of meat and animal protein in Nigeria is estimated at about 8g per caput per day, about 27g less than the minimum requirement by the National Research Council of the United State of America. Despite the progress made in pig production, current production levels especially in the developing countries are still less than the biological potentials of pigs.
Pig production in Nigeria today, has been adversely affected by a number of factors, which can be traced to environmental, nutritional, management and perhaps, genetic factors. When a stock with high genetic potential is in place, these other factors need to be totally controlled before high production will be achieved. Controlling these, will impact positively on the animals’ overall productivity.
Again, the fear created by the emergence of avian influenza (avian flu) has negatively affected animal protein intake of Nigerians. The large number of backyard household poultry enterprises have reduced due to the dread of the ominous consequences of the avian flu outbreak. This has therefore kept poultry products out of the reach of the poor urban and rural dwellers.
Pig production therefore, seems to be the likeliest and quickest means of solving the problem of insufficient animal protein intake, especially in the Southern and Middle-Belt zones of Nigeria, where pork is not discriminated against.
Also, considering the sustained pressure on livestock producers to reduce environmental impacts and optimize animal welfare, the on-going pursuit of advances in nutrition of which this research is part of, will be fundamental to the sustainability of pig production. Pig and poultry unlike ruminants, according to Preston (1990) do not produce methane and therefore are regarded as being environmentally friendly.
Among the factors that militate against animal performance, biological free radicals have been strongly implicated as one of the major causes of poor performance and low productivity in a high intensive animal production. In the event of the failure of the tissue antioxidant defense system to stabilize the activities of the free radicals, which have potentially detrimental effects on animal performance and are highly reactive, these continue to be generated leading to tissue and cell destructions. This will have very negative effects on the productive potential of the animals. Therefore, delivery of supplemental antioxidant vitamins to domestic animals in confinement might improve health and performance outcomes by reducing the effects of oxidative stress to which these animals are presumably exposed. The health outcome of morbidity and the production outcomes of weight gain and feed conversion ratio, are expected to be improved.
Supplementation with levels of feed additives has been used in swine feeds since 1950’s for improved growth rate and feed efficiency and to maintain pig performance. The most effective use is in the diets of weanlings and young growing pigs, but good responses are also obtained in finisher and breeding swine (Zimmerman, 1986).
The consistent effectiveness of feed additives in enhancing pig performance has led to their extensive use in swine feeding industry. Cromwell (2001) estimated that 80 to 90 % of all starter pig feeds, 70 to 80 % of all finisher pig feeds and 40 to 50 % of all sow feeds, are fortified with one form of additives or the other. Vitamins however, are not excluded from these additives that enhance and promote the performance of animals.
Vitamin E is a fat soluble vitamin of plant origin, essential for the integrity and optimal function of the reproductive, muscular, circulatory, neurons and immune systems. It is known for its role as an anti-oxidant, protecting unsaturated bond of cellular membrane phospholipids against free radical attack (Tappel, 1972). The immuno-modulatory effects of vitamin E, have been demonstrated in human and variety of animal species and were most evident in very young, very old and immunocompromised individuals (Tengerdy et al., 1984; Meydani, 1995).
Vitamin C is a white crystalline acid, which is widely distributed in certain fruits and vegetables. Its deficiency may lead to scurvy (Hartman –Petersen and Pigford, 1984). It is generally assumed that pigs can synthesize vitamin C and do not need dietary supplementation in most conditions (N.R.C, 1998). However, there is evidence that in certain conditions, pigs may need supplemental vitamin C for maximum weight gain (Yen and Pond, 1981).
Vitamins E and C are primary antioxidants in biological systems that break the chain of lipid peroxidation (Gey, 1998). Hoechler and Marquardt (1996) showed that vitamin C enhanced the biological efficacy of vitamin E, thus, the interaction between vitamin E and C affected performance in growing pigs.
1.1 STATEMENT OF PROBLEM
In an intensively managed piggery, pigs experience both low and high levels of antigen exposure. This type of husbandry predisposes the animals to infection and stress which may usually arise from the metabolic products of the animals and other factors as a result of the animals’ confinement.
Due to infection and stress, the immunity of the pigs may be compromised leading to poor performance. Therefore, in order to achieve high efficiency in both growth and reproductive performance of pigs, there is a great need of dietary vitamins E and C supplementation for pigs. Vitamins E and C are known to possess both antioxidant and immuno-modulatory properties that will enable pigs exposed antigenically to perform optimally.
1.2 OBJECTIVES OF THE STUDY
The broad objective of the study was :-
To evaluate the effect of dietary combinations of different levels of vitamins E and C on some performance characteristics of the pigs.
The specific objectives were to:
(i) to assess the growth performance of weaner pigs fed combinations of different levels of vitamins E and C .
(ii) to evaluate the effect of the combinations of vitamins E and C on the reproductive performance of gilts.
1.3 JUSTIFICATION OF THE STUDY
Ayo and Oladele (1996) noted that in order to achieve high rate of efficiency and live weight gain of pigs, there is a great need of vitamins E, C and A supplementation for pigs experiencing low or high levels of antigen exposure. Intensive pig production requires fast growing strains, usually at high stocking densities and in a more confined state.
With this type of husbandry, flocks are highly susceptible to infectious agents and stressful conditions, which may arise, not only from the metabolic products of the animals in a confined state but also from other factors. These infectious agents and the stressful conditions, may compromise the immune potentials of the animals thereby reducing their ability to perform optimally. In this regard, the significance of vitamins E and C which are known to have antioxidant and immuno-responsive properties can not be over emphasized.
When pigs are intensively raised, they are antigenically exposed. This results in immune system activation. Therefore, the dietary inclusion of antioxidant vitamins such as vitamins E and C in an intensively managed piggery could potentially minimize negative effects of free radicals on the productivity of farm animals.