|Livestock Research for Rural Development 28 (2) 2016||Guide for preparation of papers||LRRD Newsletter||
Citation of this paper
This study was carried out to assess the factors affecting the growth performance of Ashanti Black pig (ABP) under guinea savanna conditions. Performance testing records on 626 ABP piglets (292-males and 334-females) over a 7-year period were used. The performance parameters considered includes birth and weaning weights, pre and post-weaning average daily gain (ADG), pre- and post-weaning mortality rates and litter size.
The mean birth weight obtained in the present study was 1.02 kg. Pre-weaning average daily weight gain of 120 g, weaning weight of 6.16 kg and post-weaning average daily gain of 100 g were also recorded. Litter size, pre- and post-weaning mortality rates were 7.5 and 16.9% each, respectively. Males recorded higher (P<0.05) post-weaning ADG than their female counterparts. Similarly, birth weight and subsequent growth performance decreased (P>0.05) with increasing litter size. Pre-weaning mortality rate also increased (P<0.05) with increasing litter size beyond litter size of 10. Under guinea Savanna conditions, males grow faster than their female counterparts during the post-weaning period. Also, There is an inverse relationship between litter size and growth performance of piglets, and direct relationship between litter size and pre-weaning mortality rate for litter sizes beyond 10.
Keywords: average daily gain, birthweight, litter size, piglet, weaning weight
Interest of late has been generated in indigenous livestock breeds in Sub-Saharan Africa. These indigenous breeds are known to be able to survive harsh environmental conditions such as very high temperatures and poor nutrition. The Ashanti black pig (ABP) is one of such indigenous breeds. The history of pigs in Sub-Saharan Africa is blurred by the circumstance that very large numbers of European pig breeds were brought to all parts of the continent with European contact (Blench 2000), but phylogenetic analyses indicate that the ABPs are closer to European and Chinese breeds, than other West African and Ghanaian breeds (Osei-Amponsah et al 2015). It is one of the most commonly found breeds of livestock in Ghana. It is generally a black, small, short-bodied animal with a relatively long and narrow head, and a prolonged snout (Devendra and Fuller 1979; Barnes and Fleischer 1998). It is known to be hardy, tolerant to most common diseases and has the ability to survive under poor management and extremes of environmental conditions (Fetuga et al 1976; Ahunu et al 1995; Darko and Buadu 1998). According to Devendra and Fuller (1979), the Ashanti black pig has a low growth and reproductive performance; its average mature body weight is 60 kg with low litter size (5-7 piglets) and high (55.6 %) pre-weaning mortality. They have poor body conformation and a slow growth rate compared to the exotic breed (Holness l99l; Tweneboah 2000). The local breeds cope better with extensive and semi-intensive systems of rearing than the foreign breeds (Tweneboah 2000). The author further indicated that, low productivity was due to erratic and seasonal supplies of feed resulting in irregular breeding of sows, high rate of piglet mortality and low growth rate. Like its ancestors, the domestic pig responds to various environmental cues in an effort to maintain itself in physical and psychological harmony with its surroundings. Although, stress is generally considered to be suppressive to reproductive function, the initial response to a stressor is often stimulatory and therefore has a beneficial effect on reproduction (Varley 1994).
Half of Ghana's ABP are located in Northern Ghana (Barnes 1994). According to Otchere et al (1997), the pig is important for three reasons: firstly, it provides a source of income free from socio-cultural linkages and taboos of ownership. Secondly, it provides a rich source of manure, an important product for areas with depleted cattle stock. Thirdly, it is the only livestock for which women have a clear advantage over men, due to their ability to feed them with available waste from the kitchen. As such, investment into the pig industry in the distribution could provide the entire family an increasing income. Pig and poultry manure are best for vegetable farming as compared to cow dung, which releases its nutrients more slowly.
Several factors affect the growth performance of pigs, including birth weight, sex, weaning weight (Poore and Fowden 2004) and management practices such as feeding (nutrition; Maryrose et al 1966), and housing. Less research attention has however been directed at the effects of these factors specifically on the Ashanti Black pigs. The study was specifically designed to investigate the effects of sex of neonate, season of birth (Climatic season) and litter size on Birth weight, pre-weaning average daily gain, post-weaning average daily gain up to 1-year post-partum, pre- and post-weaning mortality rates in Ashanti Black pigs.
Data was obtained from the National Pig Breeding Station of the Animal Production Directorate, Ministry of Food and Agriculture (MoFA), Babile. Babile is located in the Lawra District of the Upper West Region (UWR) of Ghana and lies within latitude 10º 30' W and longitude 2º and 3° N. The vegetation is Guinea Savannah. The station’s mandate is to improve the Ashanti Black Pig (ABP) as an indigenous Ghanaian breed.
The floor of the pen is made of concrete, gently sloping, and roofed with aluminum sheets. Animals are fed twice daily and water is provided ad-libitum. The pigs are intensively kept and hand mated. Sows farrowed in individual pens, where they received the needed care and attention with their piglets, until weaning. The pigs are fed daily on diets compounded from conventional and non-conventional feed ingredients including maize, fish meal, wheat bran, oyster shells and salts, as well as agricultural by-products (Soya bean meal, Pito mash and baobab leaf meal). Feeding patterns are not varied seasonally, except baobab leaf meal, which is less available in the dry season. This is a rich source of vitamin and protein. Lactating sows are fed ad libitum from farrowing until weaning with rations containing 16% crude protein (CP). Creep feeding starts 3 weeks post-partum using diets containing 20% CP. Sows are flushed two weeks following weaning (42 days) with rations high in energy (13.5 MJ/kg ME) and protein (18% CP). The weights of piglets are taken after birth, 60, 90, 120, 180, 240 and 365 days.
Data was obtained from performance testing records of 626 piglets born between 2008 and 2015. The identity numbers of piglets, their dates of birth, dates of weaning and weights over 60, 90, l20, 180, 340 and 365 day periods were recorded. The pre-weaning average daily gains, and average monthly weight gains were then calculated. The parameters recorded were as follows:
(i) Birth weight: Birth weight of the piglets was taken within 24 h post-partum.
(ii) Pre-weaning average daily gain (PWADWG): This was defined as the average weight gain per animal per day from birth until weaning, and was calculated as the average of the difference between the birth and weaning weight.
(iii) Post-weaning average daily gain (PWADG): This was defined as the average weight gain per animal per day from weaning until one year of age, and was calculated as the average of the monthly weight gain from weaning until one year of age.
(iv) Weaning weight: This is the weight of the animals taken 42 days after birth, when piglets were weaned.
(v) Sex of Piglets and season of birth: The sex of the piglets was determined at birth and categorized into males and females. Piglets were also categorized into dry and wet season births based on the climatic season into which a piglet was born.
(vi) Other parameters: The other parameters recorded were litter size, pre- and post-weaning mortality rates. Pre-weaning mortality rate was calculated based on the sample size originally at the beginning of the study, while post-weaning mortality was estimated based on sample size after subtracting pre-weaning mortality.
Six hundred and twenty-six animals were used for the study. Two hundred and ninety-two (292) were males, while the remaining 334 were females. Three hundred and eighty-five (385) were born in the dry season, while 241 were born in the wet season. Except for birth weight and pre-weaning mortality rate estimation, the number of animals used for analysis in each case were lower than the total number of piglets used due to incomplete records resulting from mortalities.
Data was analyzed using the t-test (2 tailed) to determine the effects of sex and season of birth on the growth performance of Ashanti Black pigs. The chi-square procedure was used to determine the effects of the aforementioned parameters and litter size on pre- and post-weaning mortality rate, while analysis of variance for completely randomized design was used to ascertain the effects of litter size on growth performance of Ashanti Black pigs, and means separated by Tukey’s Test. All comparisons were done at 5% level of significance.
Average pre-weaning and post-weaning growth parameters, litter size and mortality rates in the Ashanti Black Pigs are shown in Table 1. Birth weight of piglets ranged from 0.75 to 1.25 kg. This range fell within the birth weights observed by Poore and Fowden (2004; 0.08 to 1.40 kg and 1.65 to 2.40 kg) in exotic breeds, respectively.
|Table l. Pre-weaning and post-weaning growth and mortality rates in Ashanti Black pigs.|
|Parameter||Number of animals||Range||Mean ± SEM|
|Birth weight (kg)||626||0.75-1.25||1.02 ± 0.30|
|PWADWG (g)||520||89.0 -167.0||120.0 ± 3.20|
|Weaning weight (kg)||520||5.2-8.6||6.20 ± 0.90|
|PWADG (g)||432||50.5-130.2||100 ± 3.00|
|Weight at 1 year (kg)||432||32.2-55.8||51.3 ± 2.00|
|Litter size||84||2-15||7.5 ± 1.0|
|*Pre-weaning mortality rate (%)||626||
|*Post-weaning mortality rate (%)||520||
|SEM: Standard error of mean
The range reported in the local breeds is narrower, and this may be explained by two hypotheses. First, this breed of pig has not been intensively selected for meat production. Secondly, poor nutrition of the dam leading to her inability to adequately provide for both her needs and that of the foetus during the gestation period. This assertion is supported by the fact that the quality and quantity of feed formulated for the pigs is dependent upon budgetary allocation by the Government and not the production requirement of the animals. According to Maryrose et al (1966), nutrition of the sow during breeding or gestation has an influence on the pre-weaning growth of piglets. This was confirmed by Baffour-Awuah et al (2005), whose study was over a 4-year period (1996-1999), with the year 1996 recording the highest birth weights. The researchers attributed their observation to better management of the sows at the start of the project, which consequently did not reflect in the presuming years. The average birth weight recorded in the present study was higher than the 0.85 Kg and 0.71 Kg reported by Sudhakar and Gaur (2003) and Darko and Buadu (1998), respectively, but similar to that reported by Alenyorege and Kawuribi (2002; 1.04 Kg) at the same breeding station. The mean pre-weaning average daily weight gain recorded from the study was l20 g/day with a range of 89-167.0 g/day. The mean value was higher than what was reported by Darko and Buadu (1998; 100g/day). The weaning weight of 6.2 kg was lower than the value reported by Alenyorege and Kawuribi (2002; 6.7 kg), but higher than what was recorded in the herd kept at KNUST (4.91 kg) (Darko and Buadu 1998). According to Mahan and Lepine (l991), gain and feed intake were higher as weaning weight increased; consequently, fewer days were required for the heavier-weight weaned pigs to reach a high final weight. Higher body weight requires higher feed intake which results in higher muscle build up. According to Tokach et al (1992), each additional feed intake gave an advantage at weaning and translated into approximately 1 kg weight gain by day at post weaning, the authors however indicated it was not clear if this represents the inherent growth potential of the heavier pig or whether similar advantages accrued from management systems which affected weaning weight. Generally, performance of piglets up to weaning is more attributable to the sow than to genetics. Pigs which were heavier at weaning maintained their weight superiority to maturity (Tokach et al 1992). The post weaning ADG recorded in the present study (100 g) was significantly lower than the 130 g and 149.6 g reported by Wabacha et al (1999) and Baffour-Awuah et al (2005), respectively. Figure 1 illustrates interactions between the sow and its newly farrowed litter, while figure 2 shows growers, two weeks following weaning.
|Figure 1. Ashanti Black sow and her piglets|
The average litter size during the study was 7.5. This compares favourably with those reported by Darko and Buadu (1998; 7.7) and World Bank report (1992; 6). Out of the 626 piglets used for the study, 520 piglets were weaned, and the overall mortality rates were 16.9% each, both for the pre- and post-weaning periods (Table 1).
|Figure 2. Eight-week old Ashanti Black pigs (ABP)|
The pre-weaning mortality rate recorded in the present study was similar to the 15.4% and 18.8% reported by Fetuga et al (1976) and Darko and Buadu (1998), respectively, in the indigenous breeds of pigs, but much lower than the figures reported in an earlier study in the ABP (Baffour-Awuah et al 2005; 22.3%) and Large white (Holman 1976 and Okai et al 1982, 25.2% and 22.7%, respectively). Figure 3 shows the growth pattern of ABP from birth until one year of age. This pattern is similar to the one reported by Alenyorege and Kawuribi (2002) after the National Livestock Services Project (NLSP). It however represents a more improved pattern than what was reported by these authors before the project. The highest weight they reported prior to the improvement project was about 27 kg at 1 year of age, while the post project improvement was reported as an average of 50 kg, nearly an increase by 2-fold.
Effects of sex on birth and weaning weights, pre- and post-weaning ADG and mortality rates: Effects of sex and season on all the growth performance parameters studied are shown in Table 2. No differences (P>0.05) were found between male and females in birth and weaning weights. Contrary to this observation, Rao et al (2004) and Poore and Fowden (2004) reported higher weaning weights in males than females, while Darko and Buadu (998) reported the reverse, females were heavier at birth than their male counterparts.
Similarly, no difference (P>0.05) was found between male and female piglets in pre-weaning average daily gain. Similar observation was made by Baffour-Awuah et al (2005) in the same breed of pigs. In Blended goats, however, Das and Sendalo (1991) reported significantly higher pre-weaning growth rates in females than their male counterparts. Males had significantly (P<0.05) higher post-weaning growth rate than their female counterparts. This agrees with the findings of several workers (Le Cozler et al 1998; Barnes and Fleischer 1998 and Baffour-Awuah et al 2005) in the same breed of pigs.
No differences (P>0.05) were found between male and female pigs in pre- and post-weaning mortality rates, even though females tended to be higher in both parameters than their male counterparts (Table 2). Similarly, Barnes and Quainoo (1985) found No difference between male and females in pre-weaning mortality rate in ABP. In contrast to these findings, Baffour-Awuah et al (2005) reported a higher mortality rate in males than females. The authors, however, gave no reasons for their observations.
No differences (P>0.05) were noted between the wet and dry season in all the growth parameters studied. Prunier et al (1993) however reported higher live weights in late winter and concluded that temperature may have a greater influence on sow and litter performance than photoperiod. Similarly, Fitas et al (2001) and Larson and Honeyman (2000) observed that post weaning average daily gain and feed efficiency were higher in all 3 seasons (Spring, Summer and Winter). This difference in performance between temperate and tropical breeds is attributable to the fact that temperate breeds store more fat to counteract cold in the wet season, compared to their tropical counterparts which experience a longer dry spell and therefore do not develop that magnitude of subcutaneous fat.
Season of birth did not significantly (P>0.05) influence pre- and post-weaning mortality rates in the Ashanti Black pigs. However, pre- and post-weaning mortality rates were very high in both seasons. In contrast, Ketchem and Rix (2012) reported higher pre-weaning mortality rates in exotic breeds during the months of July and August, coinciding with the hot summer. Similar observations were made by Li and associates (2010). Even though pre-weaning mortality rates tended to be higher in the dry hot season than wet season, the differences were not statistically significant. The figure (30%) reported by Li et al (2010) was nearly twice that reported in the present study. This may be attributed to the fact that the ABP is a tropical breed, and therefore, less prone to heat stress than the temperate breed studied by Li et al (2010). The figures (12% and 12.6% on US and Canadian farms, respectively) reported by Ketchem and Rix (2012) were, however, much lower than the 18.2% and 14.9% reported in the ABP during the wet and dry seasons, respectively. Ketchem and Rix (2012) reported that improved farrowing management on American and Canadian farms helped save some piglets. The poor performance observed in the ABP irrespective of season is, therefore, attributable to poor farrowing management.
Litter size at birth significantly (P<0.05) influenced growth performance of ABP. Birth weight was highest (1.2 kg) for piglets from a litter of 6, followed by 7 and 8, and began to decline thereafter, until it was lowest for piglets belonging to a litter of 14-15, indicating that litter size 6-8 is optimum for higher birth weight in the ABP under the prevailing management conditions. In a study by Baffour-Awuah and associates (2005), however, piglets from a litter of 5 had the highest birth weight. The most recurring litter size was 7, while the least recurring was 15. Individuals from litters of between 5 and 8 had better pre- and post-weaning growth performance than those with higher litter sizes. In general, birth weight, pre- and post-weaning growth performance of piglets decreased with increasing litter size. Similarly, Okai et al (1982) reported that birth weight and pre- weaning growth rate in piglets tended to decrease with increasing litter size. These differences in early postnatal growth of piglets have largely been attributed to maternal effects such as milk availability, the number of individuals sucking and their vitality and aggressiveness (Le Cozler et al 1998).
Litter size at birth significantly (P>0.05) influenced both pre- and post-weaning mortality rates in ABP. Except the piglets from litter size 3 and 4, which were exceptionally higher in pre-weaning mortality, pre-weaning mortality generally began to increase from litter size 11 (27.3%), until it got to 40% at litter size 15. This phenomenon is attributable to competition at sucking due to the number of piglets involved, likely reducing the level of immunoglobulin ingested in milk during the immediate post-partum period, and therefore exposing the piglet to higher risk of infection, subsequently. Baffour-Awuah et al (2005), however, noticed no trend in pre-weaning mortality rate that could be attributable to litter size.
|Table 2. Effects of sex and season of birth on growth performance and mortality rate in Ashanti Black pigs (ABP)|
|Parameter||No. of piglets||Birth weight
|PWM||X²(0.05)||POWM X² (0.05)|
|1.04 ± 0.2
1.02 ± 0.2
|120 ± 2.86
120 ± 3.50
|6.23 ± 0.90
6.13 ± 0.91
|120 ± 6.90*
100 ± 8.20*
|Dry||231||1.03 ± 0.1||120 ± 3.30||6.11± 0.80||100 ± 7.20||18.2||0.327||19.0 0.615|
|Wet||201||1.01 ± 0.1||120 ± 3.30||6.09 ± 0.80||110 ± 7.41||14.9||14.5|
PWADWG: Pre-weaning average daily weight gain, PWADG: Post-weaning average daily weight gain. Values were presented as Mean ± Standard error of mean.
|Figure 3. Growth pattern in Ashanti Black pigs during a 1 year period|
|Table 3. Effects of litter size on growth performance of Ashanti Black pigs during a 1 year period|
|Litter size||Frequency||Birth weight (kg)||PWADWG (g)||Weaning weight (kg)||PWADG (g)||PWM
|Means within a column having no superscript in
common are significantly different (P<0.05);
PWADWG: pre-weaning average daily weight gain; PWADG: Post-weaning average daily weight gain; PWM: pre-weaning mortality rate; POWM: post-weaning mortality rate.
The authors wish to thank Mr. Benjamin Alenyorege, a former farm manager of the Babile Pig Breeding Station, and the entire workforce at the breeding station for their invaluable assistance during data collection.
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Received 13 November 2015; Accepted 22 January 2016; Published 1 February 2016
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