Genetic analysis of post-weaning growth traits in a simple crossbreeding experiment between Gabali and Hyplus line rabbits

A simple crossbreeding experiment between Gabali (G) bucks and Hyplus (H) does was performed to estimate crossbreeding effects for post-weaning growth traits (body weight at 5 (BW5), 7 (BW7), 9 (BW9), 11 (BW11), and 13 (BW13) weeks of age and daily weight gains (DG) during (DG5-7), (DG7-9), (DG9-11), (DG11-13) and (DG5-13), weeks of age). Estimates of heritability were mostly low or moderate for growth traits and ranged from 0.12 to 0.35 for body weights and 0.05 to 0.66 for daily weight gains. The percentages of direct additive genetic effects on body weights favored (p ≤ 0.01) the Gabali breed by 22.1, 31.2, 32.8, 31.1, and 25.2% at 5, 7, 9, 11, and 13 weeks and by 35.4, 38.1, 21.9, 3.7, and 27% for DG5-7, DG7-9, DG9-11, DG11-13, and DG5-13, respectively. The percentages of maternal effects ranged from 22 to 34.8% for body weights and ranged from 4.7 to 43.4% for daily weight gains. The percentages of direct heterosis were significantly positive by 11, 19.1, 20.3, 19.7, and 16.5% for body weights at 5, 7, 9, 11, and 13 weeks and by 25.6, 27.2, 17.3, 3.5, and 17.9% for DG5-7, DG7-9, DG9-11, DG11-13, and DG5-13, respectively. These results suggest that the Gabali breed could be used as a sire-group and the Hyplus line could be used as a dam-group to create new high growth rabbit lines in Egypt.

Effect of bee pollen on growth performance, carcass traits, blood parameters, and the levels of metabolic hormones in New Zealand White and Rex rabbits

The aim was to evaluate the effect of bee pollen (BP) on performance, blood parameters, and metabolic hormones in New Zealand White (NZW) and Rex (RX) rabbits. A total of 60 six-week-old rabbits were allotted into a completely randomized design in a 2 × 3 factorial arrangement (two breeds and three levels of BP: 0, 250, and 350 mg/kg body weight). The effects of breed × BP supplementation level were non-significant for all growth performance and carcass traits, as well as the concentrations of metabolic hormones in the plasma. Meanwhile, some blood parameters (hemoglobin, packed cell volume, alanine aminotransferase, aspartate aminotransferase, and urea) were significantly affected (P < 0.05). Regardless of the effect of breed, the supplementation of BP at a dose of 350 mg/kg BW increased the final body weight (P = 0.008), average daily gain (P < 0.001), and net profits (P = 0.006). However, the rabbits treated with BP at a dose of 250 mg/kg BW showed lower average daily feed intake (- 14.45 g/d; P = 0.049) and feed to gain ratio (- 0.48; P = 0.039). In both rabbit breeds, BP at a dose of 350 mg/kg increased the concentrations of insulin-like growth factor-1 (302.62 ng/ml, P < 0.001), insulin (16.63 ng/ml, P = 0.050), and triiodothyronine (158.50 ng/dl, P < 0.001) in plasma compared with other groups. It may be concluded that intake of BP supplementation can improve the feed to gain ratios, blood indices, and metabolic hormones in different rabbit breeds. However, the appropriate dosage and the route of supplementation of BP in broiler rabbits need further research.

Genetic analysis of slaughter and carcass quality traits in crossbred rabbits coming from a diallel cross of four maternal lines

<p>An experiment was carried out to estimate the genetic group effects and the crossbreeding genetic parameters of slaughter and carcass traits using data on the rabbits that were progeny of does coming from a full diallel cross between 4 maternal lines (A, V, H and LP) mated to bucks of the paternal line R. The rabbits of the 16 genetic groups, corresponding to the type of does of the diallel cross, were distributed in 4 Spanish farms and 1 genetic group (V line) was present in all farms in order to connect records among them and to be used as reference group. Crossbreeding parameters were estimated according to Dickerson’s model. 1896 rabbits were measured for slaughter traits and 950 for carcass traits. The A and LP lines had the lowest values for dressing percentage (–1.71 and –1.98 compared with H line and –1.49 and –1.75 with the V line, respectively). The A line was the heaviest for commercial carcass weight. No relevant differences were observed between the crossbred groups for all traits. Regarding the reciprocal effects, there were significant differences in favour of A line as sire line in the crossbred AV. Regarding the combination of direct and maternal effects, the A line showed significantly higher values for cold carcass weight (133 g., 71 g. and 142 g. compared to the H, LP and V lines). For the same parameter the H line showed significantly higher averages on dressing percentages than A and LP lines, 1.44 and 2.13%, respectively. Line A also showed, in general, better direct- maternal effects than the V line. Grand-maternal effects were less important than direct-maternal ones. The estimates of maternal heterosis were, in general, negative, which could be a consequence of the positive heterosis for litter size. However, despite this relationship between growth and litter traits, it has not been common to find negative maternal heterosis in growth traits. A diminution of dressing percentage was detected in some crossbreds (AL and LV) and care must be taken if these types are used.</p>

Growth and reproductive performance of two rabbit breeds reared under intensive system in Ghana

A study on the growth and reproductive performance of two rabbit breeds was undertaken. Data on 588 kits and 97 does of California White and 574 kits and 90 does of New Zealand White rabbits reared under hot and humid environment in Ghana were taken. The reproductive performance of the two breeds, in terms of litter size at birth and weaning, litter weight at birth and weaning, kindling interval, age at sexual maturity, and gestation length as influenced by breed, season of kindling (rainy and dry), year of kindling (2005-2012), and parity (first to sixth and over) were determined. The performance of California White in terms of litter size at birth, at weaning, kit weight at birth, and age at first kindling was 5.9 ± 0.2, 4.6 ± 0.1, 54.7 ± 0.4 g, and 159.8 ± 0.2 days, respectively. That of New Zealand White was 5.9 ± 0.1, 5.1 ± 0.1, 55.2 ± 1.0 g, and 159.9 ± 0.2 days, respectively. The results obtained also showed a significant breed effects on kit weight at birth, litter weight at weaning, and mortality; whereas no significant differences (p > 0.05) were observed between the two breeds regarding the other traits measured. Parity had significant effects (p < 0.05) on all the growth and reproductive parameters measured with the exception of age at first kindling. Year of kindling also had significant effect on litter weight at birth, kit weight at birth, and at weaning (p < 0.05) but did not have any significant effect on the age at sexual maturity and mortality. Season also had significant (p < 0.05) effects on kit weight at birth, gestation length, kindling interval, and mortality with better performance experienced during the rainy season.