LITTER AND MEAN BUNNY WEIGHTS AS AFFECTED BY NZW RABBIT DOE AGE / WEIGHT AT KINDLING UNDER SEMI-ARID ENVIRONMENT OF ISMAILIA PROVINCE

LITTER AND MEAN BUNNY WEIGHTS AS AFFECTED BY NEW ZEALAND WHITE RABBIT DOE AGE / WEIGHT AT KINDLING UNDER SEMI-ARID ENVIRONMENT OF ISMAILIA PROVINCE

E.A.  Ahmed ¹.; Kishk, W. H. ¹; Hassan, N. S²and Abdel-Ghany, A. M. ¹

1. Suez Canal University; College of Agriculture; Animal Production Department; Al-Ismailia; Egypt.

1. Animal Production Research Institute; Agriculture Research Center; El-Dokki; Giza; Egypt

ABSTRACT

Data of this work were collected on Doe-records (235 litters) from NZW rabbits raised at the experimental Rabbitery, Faculty of Agriculture, Suez Canal University, Ismailia Governorate. Egypt, to investigate  the maternal effects of the rabbit does (i.e. doe weight and age at kindling) on litter and mean bunny weights at birth, 7, 14, 21 days and at 2, 3 months of age. Doe-weight-at-kindling was classified into four categories, the first was less than 3000, the 2^nd 3000-3500, the 3^nd 3500-4000 and the 4^th greater than 4000 g. with an average 3482 ± 21.068 g. Doe-age-at-kindling (in days) was grouped into four classes the first was less than 380 days, the 2^nd 380-560, the 3^nd 560-740 and the 4^th greater than 740 days, with an average of 491 ± 10.945 days.

Tests of significance revealed that doe-weight-at-kindling affected litter weight significantly at early age stages (till 14 days of bunny ages) while the results revealed highly significant doe-weight-at-kindling effect on mean bunny weight only at birth.  Age-of-doe-at-kindling proved significant effects on litter weight at birth and at 14 days post kindling, and on mean body at birth and mean body weight at birth and at 7 days post kindling. The effects of both studied factors (as they constitute fragment or subdivision of the maternal effect of the doe) were more profound at birth and faded thereafter as bunnies advance in age. Generally, the results showed that post kindling litter, and to some extent mean bunny, weights change positively as New-Zealand White rabbit does’ weight and age at kindling increases especially in younger ages. This may spot light on the pivot role played by does' weight and age at kindling in the ability of these does to support the maternal performance on the produced young.

Keywords: Weight and age of doe at kindling; litter and mean bunny weight.

INTRODUCTION

New Zealand White (NZW), as a worldwide commercial medium meat rabbit breed is remarkably participating nationwide in increasing meat production as for its fast growing and prolific features in addition to its high mothering abilities and therefore fecundity capabilities. Reproductive and productive traits are largely controlled by two different sets of genetic and non-genetic factors and their interaction. The productive capacity of a rabbit doe depends extensively upon litter traits (i.e. litter size and weight) which constitute important economic composite traits in rabbit production. In this respect, Lukefahr et al. (1990) reported that litter weight at weaning is a composite trait of litter size, individual weight of rabbit per litter, doe milk production, post-natal mothering ability and growth and survival of young from birth up to weaning. Xiccato, (1996) reported that does suffer from a severe loss of body energy during lactation, resulting in subsequent high replacement rate of young does. Therefore, at the same age, heavy does can benefit from the extra amount of body weight at the end of rearing to withstand the energy deficit during lactation period.

Therefore, the objectives of the present study were the investigation of the effects of weight (DWK) and age of doe (ADK) at kindling affecting litter and mean bunny weight traits in New Zealand White rabbits.

MATERIALS AND METHODS

Data of the present study for litter (LW) and mean bunny (MBW) weight traits were field data collected during the period extended from 2010 till 2011 on 235 litters from New-Zealand White Rabbit does (NZW). These records were belonging to the experimental Rabbitery flock of the Faculty of Agriculture, Suez Canal University, Ismailia, Egypt.

Does were housed in individual cages provided with nest boxes, feeders and automatic drinkers and fed on a commercial pelleted diet containing approximately 16.1% protein, 2.39% crude fat, 12.8% crude fiber and 2500 kcal DE/kg diet, digestible energy. Feed and water were provided for ad libitum. At the beginning of the experimental work does were randomly ranked into groups of five to six according to the available numbers, to each a buck of the same breed was assigned as a rule indiscriminately, with just a restriction of avoiding parent-offspring and sib mating. Random mating was held approximately 7 days after kindling at when does were transferred to the cage of its assigned buck to be mated. Pregnancy was determined by palpation 10 days following mating. Females that failed to conceive were returned to the same assigned buck to be re-bred. All thorough the entire period of the study, each buck was allowed to sire all his litters from its own assigned female group. Does which failed to become pregnant three times progressively were culled.

Light was allowed 14-16 hr. per day during the period of the study using ordinary light bulb lamps, which were distributed to provide an approximately light intensity of 4.5 watt/M. Animals were contemporaneous to each other and they have been subjected to the same managerial and environmental conditions.

Litter (LW) and mean bunny (MBW) weights were almost recorded weekly from birth to 21 days post kindling and afterward at 2, 3 months of bunnies' age. Doe-weight-at-kindling (in grams) was classified into four categories, the first was less than 3000, the 2^nd 3000-3500, the 3^rd 3500-4000 and the 4^th greater than 4000 g. with an average 3482 ± 21.068 g. Doe-age-at-kindling (in days) was grouped into four classes the first was less than 380 days, the 2^nd 380-560, the 3^rd 560-740 and the 4^th greater than 740 days, with an average of 491 ± 10.945 days. Data of does' LW and MBW traits for NZW rabbits were analyzed using SAS 8 (1999). The linear fixed model adopted for the analysis comprised the effects of weight and age of doe at kindling. The basic form of the general linear mathematical model is:

Y = Xß + e

 Where: Y = An (n x 1) observational column vector, X = Incidence matrix of zeros and ones which relating records to the appropriate fixed effects, ß = The vector of unknown fixed effects, e = The vector of random error.

Because of too many empty cells of the cross effect between doe weight and age at kindling, it was not possible to account for the interaction between the two studied factors.

RESULTS AND DISCUSSIONS

Doe-weight and age-at-kindling Effects:

Tests of significance revealed that doe-weight-at-kindling affected litter weight significantly (P < 0.05; P < 0.01 & P < 0.0001) at early age stages (till 14 days of bunny ages) while the results revealed highly significant doe-weight-at-kindling effect on mean bunny weight only at birth (Tables 1& 2).  Age-of-doe-at-kindling proved significant effects (P < 0.05; P < 0.01; P < 0.001 & P < 0.0001) were detected on on litter weight at birth and at 14 days post kindling, and on mean body at birth and mean body weight at birth and at 7 days post kindling (Tables 3 & 4).  The effects of both studied factors (as they constitute fragment or subdivision of the maternal effect of the doe) were more profound at birth and faded thereafter as bunnies advance in age (Tables 1 through 4).

Table (1). Effect of different classes of New-Zealand rabbit does’ weight at kindling on litter weight (g.) from birth (LWB) till the 3^rd month (LW3M) post kindling.

Table 2. Effect of different classes of New-Zealand does’ weight and age at kindling on mean bunny weight (g.) from birth (MBWB) till the 3^rd month (MBW3M) post kindling.

Lukefahr et al., (1983) detected significant differences due to Age-of-doe-at-kindling (ADK) on litter weight at birth. On the contrary, Ahmed (1997) and Amin et al., (2005) at birth and at weaning and Nofal et al. (1999) at 6 and 10 weeks of age; were not capable to reveal a significant effect for age-of-doe-at-kindling on litter weight.

Rommers et al., (2002)  reported that heavy does compared medium and small does had a higher litter weight at 16 days  of  lactation (P < 0.05) and without significant at 30 days of lactation and showed that no differences in mean kit weight at weaning due to the does weight groups. Kumar et al., (2001) was able to report significant effect for doe-weight-at-kindling on the weight of her kits up to 11^th week of age.

Litter weight:

Least squares Means (Table 1) of the effects of different classes of New-Zealand White rabbit does’-weight-at-kindling on litter weights from birth till the 3^rd month post kindling (Tables 1), and the effects of different classes of New-Zealand White rabbit does’-age-at-kindling on litter weights from birth till the 3^rd month post kindling (Tables 3) showed a general trend of alteration towards being heavier with advance in does' weight or age at kindling.  However, the effect of does' weight was somewhat obvious and comprehensible. Such effect was not statistically justifiable at late stages of kits' life.

Rommers, et al., (2002)  reported that heavy does compared to medium and small does had a higher litter weight at 16 days  of  lactation (P < 0.05) and without significant at 30 days of lactation and showed that body weight group affect productive performance where occurs improve with heavy doe weight compared to other doe weight  classes.  Furthermore,  Xiccato, (1996) reported that does suffer from a severe loss of body energy during lactation, resulting in subsequent high replacement rate of young does, so the  heavier does might be able to benefit from the extra amount of body weight to overcome the energy deficit during lactation period. In the same pattern, Rommers et al., (2001) showed that heavier does had larger uterine horns and more corpora lutea on the ovaries compared with small does.

Afifi et al.(1982) ascribed the differences in litter weight with age of doe to pre- and post-natal mothering ability. Khalil, (1989) was able to reveal that significant changes in litter weight due to age of the at kindling may be due to the perplexity and confounding between age of doe and parity rank.

This may indicate that, judging from New-Zealand White rabbit does’ weight and age at kindling, does weight plays a pivot role in the ability of these does to support the maternal performance on the development of the produced young. However, taking into account the Standard errors of the least squares Means of the New-Zealand White rabbit does’ weight or age at kindling, the homogeneity of these litters ruptured upward in the two extreme weights, but rather high in those with maximum weights. This relatively high variability in outcomes of the two extremities may reveal that the effects are multi-factorial and not necessarily produced the alleged results. However, this variability is not that clear when considering the coefficient of variability (CV).

Mean bunny weight:

Tables (2 & 4) represent Least squares Means of the effects of different classes of New-Zealand White rabbit does’-weight (Table 2) and –age (Table 4) -at-kindling on mean bunny weights from birth till the 3^rd month post kindling. In most ages the changes in mean bunny weight traits follow a trend of higher doe weight or age classes gave better performance than that given by the lower two doe weight or age classes.

Rommers, et al. (2002) reported that medium and heavy does tended to have heavier kits at 16 days of lactation and it is not only the higher milk production that results in a heavier weight of the kits at weaning. Rojan, et al. (2013) reported that the highest significant least squares means were detected at tenth and twelfth week body weights of kits born out of dams weighing three kilograms or more. Form another hand, Parigi-Bini et al. (1992) and Xiccato et al. (1995) showed that Kits of small does may have compensated for the lower amount of milk available to them by consuming more pelleted feed. Rojan, et al. (2013) showed that higher mean body weights detected from 4 to 12 weeks of age  for kits born out of dams ageing from 1000 to above 2000 days with significant effect at 4, 6 and 8 week of age

In other words, the larger the does' weight or age -at-kindling, the larger the mean body weight of its bunnies, with the effect being more pronounced starting from 3500 g kindling-weight or 560 days kindling-age of the does. This may indicate that  judging from the field data of New-Zealand White rabbit does’ and semi-desert environment of Ismailia Provence, does weight and to a lesser extent age plays a pivot role in the ability to support the maternal performance of these does on the produced broiler young rabbits.

Conclusion

Using heavy doe weight may improve litter and mean bunny weight of broiler New-Zealand White rabbits. This effect was more pronounced and verified statistically at younger ages rather than at marketing ages at two- or three-months of growing rabbit kits.

Table 3.  Effect of different classes of New-Zealand White does’ age at kindling on litter weight (g.) from birth (LWB) till the 3^rd month (LW3M) post kindling.

Table 4.  Effect of different classes of New-Zealand White does’ age at kindling on mean bunny weight (g.) from birth (MBWB) till the 3^rd month (MBW3M) post kindling.

REFERENCES

Afifi, E.A., Abdella, M.M., El-Serafy, A.M. and El-Sayaad, G. A. (1982). Litter traits in rabbits as affected by feeding urea, breed group and other non-genetic factors. Seventh international Congress for statistics, Computer Science, Social and Demographic Res., pp 177-196.

Ahmed, E.G. (1997). Productive performance of different exotic strains of rabbits. Ph. D. Thesis, Fac. of Agric., Suez Canal Uni., Ismailia, Egypt.

Amin, A. A.,  Abdel-Ghany, A. M. and Ahmed, E. G.  (2005). Genetic profile on pre- and post-weaning numbers dead plus litter and gain in weight traits of Hungarian New Zealand White rabbits. The 4^th Inter. Con. on Rabbit Prod. in Hot Climates, Sharm El-Sheikh, Egypt, 65 – 74 (2005)

Khalil, M.H. (1989). Estimates of genetic and phenotypic parameters for weaning and pre-weaning body weights and gain in Bouscat and Giza White rabbit. Annals of Agric. Sci., Moshtohor, 27: 1557-1574, Egypt.

Kumar S, Gulyani R, Kumar V, Singh RN (2001). Effect of genetic and non genetic factors on weekly body weight of broiler rabbits in semi arid region of Rajasthan. Indian J. Anim. Sci., 71,(11): 1075-1077.

Lukefahr, S., Cheeke, P. R. and Patton, N. M. (1990). Prediction and causation of litter market traits from pre-weaning and weaning characteristics in commercial meat rabbits. Journal of Animal Science, 68: 2222-2234.

Lukefahr, S., Hohenboken, W. D., Cheeke, P. R. and Patton, N. M. (1983). Doe reproduction and pre-weaning litter performance of straightbred and crossbred rabbits. J. of Anim. Sci., 57: 1090-1099.

Nofal, R. Y., Abdel-Ghany, A. M., Amin, A. A.; Ahmed, E. G. and Virag Gy. (1999). Mixed model genetic analysis of litter Size and weight traits in New Zealand White rabbits reared under Hungarian conditions. Proceeding of the First International Conference on Indigenous Versus Acclimatized Rabbits, 7-9 September, (1999) Pp.: 101-108, El-Arish, Egypt.

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تأثیر وزن وعمر الأم عند الولادة على کل من وزن خلفة البطن ومتوسط وزن الخلفة بالبطن للأرانب النیوزلندى الأبیض تحت الظروف البیئیة شبه الجافة لمحافظة الإسماعیلیة

السید جمال أحمد أحمد1 – ولید حسین کشک1 – ناجى سعید حسن2 –

أحمد محمود عبد الغنى1

1. جامعة قناة السویس – کلیة الزراعة – قسم الإنتاج الحیوانی – الإسماعیلیة –  مصر.

2. معهد بحوث الإنتاج الحیوانی – مرکز البحوث الزراعیة – الدقی – الجیزة –  مصر.

تم تجمیع البیانات الحقلیة للبحث من عدد 235  بطن ناتجة من أرانب النیوزیلندی الأبیض المرباة فى المزرعة التجریبیة لکلیة الزراعة جامعة قناة السویس بمحافظة الإسماعیلیة، مصر. وذلک لتقدیر التأثیرات الأمیة لإناث الأرانب والمتمثلة  فی کل من وزن وعمر الأم عند الولادة على کل من وزن خلفة البطن ومتوسط وزن الخلفة بالبطن عند کل من المیلاد ، 7، 14، 21  یوم وکذلک عند عمر 2، 3 شهور. تم تقسیم أوزان الأمهات عند المیلاد لأربعة أقسام ، الأولى کانت لأقل من وزن 3000 جم والثانیة ما بین 3000-3500جم والثالثة  مابین 3500-4000 جم والرابعة کانت للأمهات الأعلى من 4000جم وذلک بمتوسط 3482 ± 21.068 جم  . کذلک تم تقسیم مجامیع الأمهات تبعا للعمر عند الولادة لأربعة مجامیع: کانت المجموعة الأولى للأمهات ذات الأعمار أقل من 380 یوم وتراوحت أعمار المجموعة الثانیة ما بین 380-560 یوم والمجموعة الثالثة ما بین 560- 740 یوم والمجموعة الرابعة کانت لأوزان الأمهات الأعلى من 740 یوم وذلک بمتوسط 491 ± 10.945 یوم.

أوضحت اختبارات المعنویة أن لفئات وزن-الأم-عند-المیلاد تأثیرا معنویا على وزن الخلفة بالبطن خلال فترة العمر الأولى (حتى الیوم 14 بعد الولادة)، بینما أوضحت النتائج تأثیرا عالی المعنویة لعمر-الأم-عند-المیلاد على متوسط وزن الخلفة بالبطن فقط عند المیلاد وعند 7 أیام.

هذا وتأثیر کلا العاملین المدروسین (واللذان یشکلان مرکزان هامین للتأثیر الأمی) کان أعلى ما یمکن عند المیلاد ثم بدآ بضمحلال بعد ذلک مع تقدم الخلقة فی العمر. وبصفة هامة فقد أظهرن النتائج أن وزن خلفة البطن وبدرجة أقل متوسط وزن خلفة البطن کانت فى الأرانب النیوزلندی کانت تظهر تغیرا موجبا مع الزیادة فى وزن وعمر-الأم-عند-المیلاد وبصورة أکثر وضوحا فی الأعمار الصغیرة. وربما یلقى هذا الضوء على الدور المحوری والهام الذی یلعبه العاملان المدروسان على قدرة هذه الأمهات على دعم قدراتها الأمیة لرعایة خلفاتها خاصة فی أعمارها الأولى.

أما بالنسبة لفئات عمر-الأم-عند-المیلاد فقد أظهر تأثیرا معنویا وزن الخلفة بالبطن معنویا عند المیلاد وعند 14 یوم بعد الولادة.