Livestock Research for Rural Development 21 (9) 2009 Guide for preparation of papers LRRD News

Citation of this paper

Genetic study on reproductive traits in crossbred pigs

J Sai Prasanna, M Gnana Prakash, B R Gupta and M Mahender

Department of Animal Genetics and Breeding, College of Veterinary Science, Sri Venkateswara Veterinary University, Hyderabad - 500 030, India
drsai_prasanna_reddy@yahoo.co.in

Abstract

Data on 433 farrowings belonging to half-bred and Large White Yorkshire-desi crossbred pigs maintained at Tirupati, India were subjected to least squares analysis to study the effect of genetic and non-genetic factors.

 

Significant effect of period and season of birth was observed on gestation period, litter size and litter weight at birth and weaning (8 weeks). The least squares mean gestation period was 111.49 + 0.34 days. Mean litter sizes were 6.78 + 0.11 at birth and 6.22 + 0.11 at weaning while the corresponding mean litter weights were 7.53 + 0.12 and 60.77 + 1.00 kg at weaning. Sows farrowing during rainy season had larger and heavier litters than those farrowing in other seasons.

Keywords: Gestation period, litter size, litter weight


Introduction

Improvement of reproductive traits will improve efficiency of swine production. Exotic germ plasm, when introduced into tropical climate suffers greater embryonic death losses resulting in reduced litter size. English et al (1984) opined that management modulates the variation in gestation length. It is necessary to understand the genetics of reproductive traits in crossbred pigs for zeroing in on appropriate breeding plans. Hence, the present investigation was taken up to study the effect of genetic and environmental factors on gestation period and litter traits and also to study the relationship among them.

 

Materials and methods 

Tirupati, a town in south India is located at an altitude of 160 meters above the sea level. Tropical climate with three seasons viz. summer, winter and monsoon prevail here. During summer, temperature reaches a maximum of 45 C and falls to a minimum of 13 C during winter.

 

Data on 433 farrowings belonging to two genetic groups viz. 50% Large White Yorkshire (LWY) - 50% desi and 75% LWY - 25% desi crossbreds generated over a period of 9 years (2000-2008), at the All India Coordinated Research Project (AICRP) on Pigs, Tirupati, India were subjected to least squares analysis (Harvey 1979) using fixed effects linear model to study the effects of genetic group and period and season of birth on gestation period, litter size at birth and weaning and litter weight at birth and weaning. The piglets were weaned at 8 weeks of age. Data were grouped into three periods of 3 years each viz. period 1 (2000-2002), period 2 (2003-2005) and period 3 (2006-2008). Year was divided into three seasons viz. summer (Mar-Jun), rainy (Jul-Oct) and winter (Nov-Feb). Duncan’s Multiple Range Test as modified by Kramer (1957) was employed for pair-wise comparison of means. Data corrected for significant non-genetic effects was utilized for estimating phenotypic correlations.

 

Results and discussion 

Gestation period

 

The overall least squares mean gestation period was 111.49 0.34 days (Table 1). Published literature revealed that the gestation period ranged from 111.38 to 112.9 in exotic-desi crosses (Nath et al 2002 and Prakash et al 2008).


Table 1.  Least squares means for gestation period and litter traits of crossbred pigs

 

n

Gestation period

(days)

Litter size at

Litter weight (kg) at

birth

weaning

birth

weaning

Mean

SE

Mean

SE

Mean

SE

Mean

SE

Mean

SE

Overall

433

111

0.34

6.78

0.11

6.22

0.11

7.53

0.12

60.8

1.00

Genetic group

 50% LWY

215

112

0.47

6.73

0.16

6.13

0.16

7.46

0.17

58.9

1.40

 75% LWY

218

111

0.47

6.83

0.16

6.31

0.16

7.61

0.17

62.7

1.41

Period of birth

  2000-2002

159

113a

0.55

6.81ab

0.18

6.14a

0.18

7.77a

0.20

61.9a

1.63

  2003-2005

152

111b

0.56

6.36b

0.19

5.84b

0.19

6.95b

0.21

56.3b

1.67

  2006-2008

122

111b

0.63

7.16a

0.21

6.67a

0.21

7.89a

0.23

64.1a

1.87

Season of birth

  Summer

159

113a

0.55

6.67ab

0.18

6.02ab

0.18

7.41

0.20

58.2b

1.63

  Rainy

119

110b

0.64

7.18a

0.21

6.70a

0.21

7.92

0.23

66.4a

1.89

  Winter

155

111b

0.56

6.48b

0.19

5.92b

0.19

7.27

0.21

57.8b

1.66

Means with similar superscript(s) do not differ significantly (P>0.05).


The non-significant effect of genetic group observed in the present study is in conformity with the findings of Prakash et al (2008). Significant effect of period (P<0.05) and season of birth (P<0.01) was observed on gestation period. Mukhopadhyay et al (1992) also found a significant effect of season while Das et al (2005) found a non-significant effect of season on gestation period.

 

Litter size

 

The overall least squares mean litter size in the present investigation was 6.78 0.11 at birth and 6.22 0.11 at weaning (Table1). Kumari et al (2008) and Prakash et al (2008) also found almost a similar litter size which ranged from 6.22 to 6.82 at birth and 5.54 to 6.33 at weaning in LWY-desi crossbreds. 

 

The effect of genetic group was found to be non-significant on both the litter size at birth and weaning. Tummaruk et al (2004) reported a non-significant influence of genetic group on litter traits while a significant effect was observed by Nandakumar et al (2004) and Prakash et al (2008). The genetic groups in the present investigation belong to 50 and 75% LWY-desi crossbreds and not two separate breeds and this might be the reason for the non-significant effect of genetic group on litter size observed in the present study. 

 

Both period and season of birth had significant influence on litter size at birth and weaning. Significant effect of season of birth was found on litter size (Kumari et al 2008 and Prakash et al 2008). Chhabra et al (1996) found significant effect of year on the litter size at birth and weaning.

 

Litters born during rainy season recorded a higher litter size at birth and weaning which is in agreement with Kumari et al (2008) and Prakash et al (2008). However, Deka et al (2002) and Nandakumar et al (2003) found that the largest litters at birth and weaning were observed in sows farrowing during pre-monsoon season. Season generally influences the litter traits through factors such as ambient temperature, relative humidity and availability of feed.

 

Litter weight

 

The overall least squares mean litter weight at birth was 7.53 0.12 kg, which was well within the range of 5.92 to 9.20 kg, as published literature on LWY-desi crosses (Kumari et al 2008 and Prakash et al 2008). The litter weight at weaning was found to be 60.77 1.00 kg which is also well within the range (55.14 to 64.23 kg) in LWY-desi crossbred pigs (Kumari et al 2008 and Prakash et al 2008).

 

The effect of genetic group was non-significant on both the litter weight at birth and weaning in the present study. In contrast, significant effect of genetic group on litter weight at birth and weaning was observed by Nath et al (2002), Kotirathnam et al (2002), Nandakumar et al (2004) and Prakash et al (2008) in desi, LWY and their crosses.

 

The influence of period of birth was found to be highly significant (P<0.01) on litter weight at birth and weaning. Chhabra et al (1996) also observed that the year of birth was a significant source of variation for litter traits at birth and weaning.

 

Season of birth had highly significant effect on litter weight at weaning while it had no significant effect on litter weight at birth. Higher litter weight at weaning was found for piglets born during rainy season. Available literature also revealed that litters born during rainy season were significantly heavier at weaning (Deka et al 2002; Phookan et al 2006) while Nandakumar et al (2003) found summer-born litters heavier at weaning. The higher litter weight at weaning of pigs born during rainy season appears to be due to favourable environmental conditions during the postnatal growth.

 

Correlations

 

Phenotypic correlations of gestation period with litter traits and correlations among litter traits were all high and ranged from 0.84 0.03 to 0.98 0.01 (Table 2).


Table 2.  Phenotypic correlations among gestation period and litter traits in crossbred pigs

 

LSB

LSW

LWB

LWW

GP

0.860.03

0.840.03

0.860.03

0.860.03

LSB

 

0.970.01

0.970.01

0.950.02

LSW

 

 

0.950.02

0.980.01

LWB

 

 

 

0.930.02


Kotirathnam et al (2001) also reported significant and positive phenotypic correlations among litter traits in LWY-desi crossbred pigs.

 

Conclusion

References 

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Das D, Deka D, Nath D R and Goswami R N 2005  Estimates of heritability and effects of some non genetic factors on traits of reproduction in Hampshire pig. Indian Veterinary Journal 82: 847-50

 

Deka D, Goswami R N, Mili D C and Saikia S 2002  Effect of some non genetic factors on Litter traits in Hampshire Pig. Indian Veterinary Journal 79: 588-90

 

English P, Smith W and Maclean A 1984 The sow improving her efficiency. II Edition. Ferming Press Ltd., Suffolk

 

Harvey W R 1979 Least Squares analysis of data with unequal subclass numbers. U.S. Department of Agriculture Research Science and Education Administration.

 

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Received 10 April 2009; Accepted 20 June 2009; Published 1 September 2009

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