Sarin Karthikeyan Kunnath Sakaram Durgam Gnana Prakash Manthani Sarat Chandra Amaravadhi Vol 8(9), 234-240 DOI- http://dx.doi.org/10.5455/ijlr.20171205103612
Data recorded on growth of 433 bunnies born in to 112 litters of two synthetic rabbit genetic groups APAU Fawn (FN) and APAU Black (BL), from August 2011 to September 2012, of Rabbit Research Centre, College of Veterinary Science, Hyderabad, were utilized for the present investigation to evaluate influence of genetic and non-genetic factors on pre weaning growth performance of the two breeds under study. The effect of genetic group was significant limited to a particular period of study. Season of birth exerted highly significant influence on body weight gained, with winter proving to be the promising period for growth. Litter size at birth was found to exert influence on body weight gained by each bunny in a group, with smaller groups gaining more. Genetic group, Season of birth and Litter size exerted a significant influence on Average Daily Gain (ADG) of bunnies. The overall pre-weaning mean body weight at first and fourth week ranged from 51.30 ± 0.38g to 476.39 ± 5.43g, respectively, whereas the ADG ranged from 8.86 ± 0.15g to 29.52 ± 0.73 g, for the same period.
Keywords : Average Daily Gain Body Weight Rabbit Pre-Weaning
Of late, there has been an increased awareness of the advantages of rabbit meat production in developing countries as a means to alleviate food shortages. This is largely attributable to the rabbit’s high rate of reproduction; early maturity; rapid growth rate; high genetic selection potential; efficient feed and land space utilization; limited competition with humans for similar foods and high-quality nutritious meat Cheeke (1980). The rabbit has been used as an experimental animal in genetics and reproductive physiology since long, but it was not until 1950 that the first findings on quantitative genetics were published, Venge (1950). This work paved the way for research on the genetic improvement of the rabbit for meat production. For the past few decades, extensive work has been carried out on rabbits throughout the World and India in particular. Emphasis was laid on establishing the genetic worth of each individual breed reared at different geographical regions. However, sometimes a group of rabbits available in a particular geographical region have certain distinct characteristic features that enable them to be differentiated from other genetic groups. The characteristic features of these groups need to be studied on the basis of their physical, physiological, reproductive, productive and genetic parameters.
Two synthetic genetic groups, namely APAU-Fawn and APAU-Black, were evolved from Grey Giant and New Zealand White in F2 and further generations at “Rabbit Research Centre”, Hyderabad. Selective breeding within breeds was carried out for breed stabilization and to exploit within breed genetic variation for economic traits in rabbits. Jaya Laxmi et al. (2009), carried out a preliminary work comparing the performance of FN rabbits with other established breeds of rabbit. Later on not much work was carried out exclusively on these two breeds to establish its genetic worth. The present study aims at evaluating genetic and non-genetic factors influencing growth traits of the above mentioned genetic groups.
Materials and Methods
The synthetic rabbit breeds APAU Fawn and APAU Black maintained at Rabbit Research Centre, Department of Animal Genetics and Breeding, College of Veterinary Science, Hyderabad were reared under uniform environmental conditions with proper ventilation and a temperature range of 28-30°C. About 100-150 g of concentrate mixture with a composition of 50% Maize, 22% GNC, 25% wheat bran and 3% mineral mixture was fed daily and supplemented with Alfalfa green fodder. Clean drinking water was provided throughout the day using nipple drop system. Body weights were recorded for each individual at 0 day and every weekly interval up to 4 weeks of age.
Statistical Analysis
Data generated for growth trait was subjected to least squares analysis using Proc (Procedure) GLM (General Linear Model) of SPSS (Statistical Package for Social Sciences) 15.0 and the data were corrected for significant non-genetic effects (season of birth). Litter size was divided in to three groups. The first group includes litter bearing 2 to 4 kits, second group 5 to 7 kits and third group 8 to10 kits. Season of birth were divide as winter (November to February), summer (March to June) and rainy (July to October).
Results and Discussion
Pre-Weaning Body Weight
The results obtained from least-squares analysis of variance and mean body weights at pre-weaning ages presented in Table 1 & 2.
Table 1: Least-squares analysis of variance for pre-weaning body weights
Source of Variation | Mean Sum of Squares | ||||||||||
d. f. | BW 0 | d. f. | BW 1 | d. f. | BW 2 | d. f | BW3 | d. f | BW4 | ||
Genetic group | 1 | 1.27 | 1 | 1064.36 | 1 | 10928.53** | 1 | 41.98 | 1 | 1776.76 | |
Season of birth | 2 | 2643.43** | 2 | 8648.50** | 2 | 45312.79** | 2 | 63082.74** | 2 | 57446.49** | |
Sex of bunny | 1 | 1368.71** | 1 | 10216.81** | 1 | 19631.65** | 1 | 7663.64** | 1 | 23561.39 | |
Litter size at birth | 2 | 490.61** | 2 | 4954.72** | 2 | 18169.25** | 2 | 32893.49** | 2 | 180956.87** | |
Error | 426 | 55.29 | 426 | 431.75 | 426 | 1526.78 | 426 | 4210.47 | 426 | 11190.76 |
*Significant (P≤0.05), **Significant (P≤0.01)
Table 2: Least-squares means for pre-weaning body weight (g)
n | BW O | n | BW 1 | n | BW 2 | n | BW 3 | n | BW 4 | |
Overall | 433 | 51.30 ± 0.38 | 433 | 111.20 ± 1.06 | 433 | 178.74 ± 2.00 | 433 | 273.75 ± 3.33 | 433 | 476.39 ± 5.43 |
Genetic group | ||||||||||
Fawn | 209 | 51.24 ± 0.53 | 209 | 112.79 ± 1.48 | 209 | 183.86a ± 2.79 | 209 | 273.43 ± 4.46 | 209 | 478.45 ± 7.56 |
Black | 224 | 51.35 ± 0.52 | 224 | 109.60 ± 1.46 | 224 | 173.61b ± 2.75 | 224 | 274.07 ± 4.57 | 224 | 474.32 ± 7.46 |
Season of birth | ||||||||||
Summer | 150 | 49.79b ± 0.62 | 150 | 112.49b ± 1.75 | 150 | 169.91b ± 3.29 | 150 | 263.10b ± 5.46 | 150 | 491.54a ± 8.91 |
Rainy | 153 | 47.67c ± 0.66 | 153 | 102.41c ± 1.86 | 153 | 165.86b ± 3.51 | 153 | 258.78b ± 5.83 | 153 | 452.82b ± 9.51 |
Winter | 130 | 56.43a ± 0.65 | 130 | 118.69a ± 1.84 | 130 | 200.43a ± 3.46 | 130 | 299.37a ± 5.74 | 130 | 484.80a ± 9.36 |
Sex of bunny | ||||||||||
Male | 196 | 49.50b ± 0.55 | 196 | 106.27b± 1.53 | 196 | 171.91b ± 2.89 | 196 | 269.48b ± 4.80 | 196 | 468.90 ± 7.83 |
Female | 237 | 53.10a ± 0.50 | 237 | 116.12a ± 1.40 | 237 | 185.56a ± 2.63 | 237 | 278.02a ± 4.37 | 237 | 483.87 ± 7.13 |
Litter size at birth | ||||||||||
2-4 | 137 | 50.95b ± 0.64 | 137 | 117.21a ± 1.81 | 137 | 192.40a ± 3.40 | 137 | 292.25a ± 5.65 | 137 | 506.20a ± 9.21 |
5-7 | 208 | 49.38c ± 0.53 | 208 | 105.97b ± 1.48 | 208 | 173.37b ± 2.80 | 208 | 267.65b ± 4.65 | 208 | 439.62b ± 7.58 |
8-10 | 88 | 53.56a ± 0.81 | 88 | 110.41a ± 2.28 | 88 | 170.43b ± 4.28 | 88 | 261.34b ± 7.12 | 88 | 483.34a ± 11.60 |
Means with similar superscripts within each column under each effect do not differ significantly
The genetic group had a significant influence on body weight at 2 weeks of age only, which is in partial agreement with Anitha et al. (2009) and Obike et al. (2010) who reported influence of genetic group on body weight at all ages of pre-weaning. Statistically Fawn group of rabbit gained more body weight compared to black group over the entire period of study. The overall least-squares mean body weights at birth, 1, 2, 3 and 4 weeks of age were 51.30 ± 0.38, 111.20 ± 1.06, 178.74 ± 2.00, 273.75 ± 3.33 and 476.39 ± 5.43g, respectively, which concurs well with the findings of Devi et al. (2007) and Prakash et al. (2008) at most of the ages studied, partly in accordance with reports of Lavanya et al. (2017) and were higher than the values reported by Udai et al. (2017) in Soviet chinchilla and Californian breeds of rabbit . Least-squares mean body weights at birth, 1, 2, 3 weeks and 4 weeks of age were, 51.24 ± 0.53, 112.79 ± 1.48, 183.86 ± 2.79, 273.43 ± 4.46 and 478.45 ± 7.56 g, in FN rabbits and 51.35 ± 0.52, 109.60 ± 1.46, 173.61 ± 2.75, 274.07 ± 4.57 and 474.32 ± 7.46 g, in BL rabbits, respectively. Season of birth exerted significant influence on body weights as observed in the present investigation with bunnies recording significantly higher body weights compared to other seasons at most of the pre-weaning ages recorded, which concurred well with findings of Abdel-Azeem et al. (2007) Anitha et al. (2009), Devi et al. (2007) and Poornima et al. (2002) who also reported higher body weights in winter born bunnies. Least-squares mean body weights at birth, 1, 2, 3 weeks and 4 weeks of age were 56.43 ± 0.65, 118.69 ± 1.84, 200.43 ± 3.46, 299.37 ± 5.74, 484.80 ± 9.36 g, respectively for bunnies during winter and 47.67 ± 0.66, 102.41 ± 1.86, 165.86 ± 3.51, 258.78 ± 5.83 and 452.82 ± 9.51 g, for bunnies born during rainy season. Sex of bunny exerted significant influence on body weights at all pre-weaning ages studied, except at 4th week of age. In concurrence with reports of Lavanya et al. (2017) and partly in accordance with Udai et al. (2017). Contrary to the findings of Marykutty and Nandakumar (2000) and Abdel-Azeem et al. (2007) who observed a non-significant effect of sex on body weights. Females recorded heavier body weights compared to males at all ages of per-weaning period studied.
Litter size at birth had high significant effect on body weight at all ages, which is in agreement with findings of Anitha et al. (2009), with bunnies born in to smaller litters recording heavier body weights, due to the fact that the relative share of milk per kit decreased as the litter size increased, which agrees well with a series of findings of Poornima et al. (2002), Castellini et al. (2003) and Prakash et al. (2008), who reported that bunnies born during summer and in to smaller litters recorded heavier pre-weaning body weights.
Average Daily Gain (ADG)
Least-squares analysis for variance and mean ADGs during pre-weaning period are presented in Tables 3 and 4, respectively.
Table 3: Least-squares analysis of variance for pre-weaning ADG
Source of Variation | d. f. | Mean Squares | |||
1week | 2 week | 3week | 4week | ||
Genetic group | 1 | 16.73 | 95.34* | 278.48* | 21.96 |
Season of birth | 2 | 78.77** | 412.11** | 32.44 | 1941.80** |
Sex of bunny | 1 | 107.48** | 41.45 | 35.62 | 168.83 |
Litter size at birth | 2 | 101.01** | 124.98** | 154.99* | 1229.00** |
Error | 425 | 6.49 | 16.97 | 45.33 | 151.97 |
*Significant (P≤0.05), **Significant (P≤0.01)
The effect of genetic group was found to be significant on ADGs at 2 and 3 weeks of age. Which concurs well with the findings of Oke et al. (2004), who stated significant differences for ADG among three breeds of rabbits studied, NZW, Dutch and Chinchilla and also with the findings of Anitha et al. (2009) in NZW, SC and FG breeds of rabbits. The overall least-squares mean ADGs at 1, 2, 3 and 4 weeks age were 8.86 ± 0.15, 9.88 ± 0.24, 14.00 ± 0.39 and 29.52 ± 0.73 g, and the corresponding means were 9.06 ± 0.19, 10.36 ± 0.31, 13.18 ± 0.51 and 29.75 ± 0.94 g for FN rabbits and 8.66 ± 0.19, 9.40 ± 0.31, 14.82 ± 0.52 and 29.29 ± 0.95 g for BL rabbits, respectively. The FN rabbits recorded higher ADGs compared to BL rabbits, though non-significantly at some periods. These estimates were lower than the mean ADGs reported by Medellin and Lukefahr (2001), Abou-Khadiga et al. (2008) and Ouyed et al. (2008) and higher than the values reported by Devi et al. (2007).
Table 4: Least-squares means for pre-weaning ADG (g)
N | ADG 1 | n | ADG 2 | n | ADG 3 | N | ADG 4 | |
Overall | 433 | 8.86 ± 0.15 | 433 | 9.88±0.24 | 433 | 14.00±0.39 | 433 | 29.52±0.73 |
Genetic group | ||||||||
Fawn | 209 | 9.06 ± 0.19 | 209 | 10.36±0.31 | 209 | 13.18±0.51 | 209 | 29.75±0.94 |
Black | 224 | 8.66 ±0.19 | 224 | 9.40 ± 0.31 | 224 | 14.8 ± 0.52 | 224 | 29.29±0.95 |
Season of birth | ||||||||
Summer | 150 | 9.38a ± 0.22 | 150 | 8.54b ±0.36 | 150 | 13.76a±0.59 | 150 | 33.79a±1.09 |
Rainy | 153 | 8.00b ±0.23 | 153 | 9.19b ±0.38 | 153 | 13.65a±0.62 | 153 | 27.68b±1.15 |
Winter | 130 | 9.21a ± 0.23 | 130 | 11.91a±0.38 | 130 | 14.58a±0.62 | 130 | 27.10c±1.15 |
Sex of bunny | ||||||||
Male | 195 | 8.35 ± 0.20 | 195 | 9.56 ± 0.32 | 195 | 14.29 ±0.52 | 195 | 28.89 ±0.96 |
Female | 238 | 9.37 ±0.19 | 238 | 10.19 ±0.31 | 238 | 13.70 ±0.50 | 238 | 30.16 ±0.92 |
Litter size at birth | ||||||||
2-4 | 62 | 10.21a±0.32 | 62 | 11.26a±0.53 | 62 | 15.68a±0.86 | 62 | 30.89a±1.58 |
5-7 | 284 | 8.29b ±0.15 | 284 | 9.81b ±0.25 | 284 | 13.37b±0.41 | 284 | 26.12b±0.75 |
8-10 | 87 | 8.09b ±0.28 | 87 | 8.56b ±0.45 | 87 | 12.95b±0.74 | 87 | 31.57a±1.36 |
Means with similar superscripts within each column under each effect do not differ significantly
Influence of season of birth was found to be highly significant on ADGs at all ages, except at 3 weeks age in accordance with observations of Gupta (1998), EL Maghawry et al. (1999) and Anitha et al. (2009). Least squares mean ADGs at 1, 2, 3 and 4 week of age were 9.21 ± 0.23, 11.91 ± 0.38, 14.58 ± 0.62 and 27.10 ± 1.15 g, in rabbits born during winter and 9.38 ± 0.22 , 8.54 ± 0.36, 13.76 ± 0.59 and 33.79 ± 1.09 g, in rabbits born during summer respectively. In general, the bunnies born during winter season recorded significantly higher ADGs at most of the ages studied when compared to those born during summer and rainy seasons.
Female recorded higher ADGs compared to male at most of the ages, though non-significantly. Sex of the bunny did not had a significant influence on ADGs at most of the ages except at 1 week of age. Gupta (1998) also observed a non-significant effect of sex on ADG in rabbits. Litter size at birth exerted significant effect on ADGs studied at all ages, in the present investigation and this agrees well with the observations of Gupta (1998), EL Magahwary et al. (1999), Borthakur et al. (2002), Devi et al. (2007) and Anitha et al. (2009). However, Prayaga and Eady (2003) observed a non-significant influence of litter size at birth on ADG. Rabbits born in to smaller litters recorded significantly higher AGDs at all ages of pre-weaning period (except at 4 week of age) compared to those born in to medium and larger litters.
Conclusion
Results of the present study have revealed that the FN rabbits had better performance compared to BL rabbits with respect to the body weights and growth rates at pre-weaning ages. However, a comprehensive study on these two genetic groups would be helpful further in establishing their genetic worth.
Acknowledgement
The authors are extremely thankful to authorities of the institute, College of Veterinary Science, Rajendranagar for their support and guidance in carrying out the research.
References