World Rabbit Science - Vol. 29 (1)-2021
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- Challenging the growing rabbit with a moderately pathogenic E. coli under ad libitum or limited feed intake conditions: impact on digestive physiology, bacterial communities, and on post-weaning growth
- Effects of dietary supplementation with taurine on production performance of Angora rabbits
- Identification of nucleotide variation of growth hormone gene in rabbit populations reared in Bulgaria
- Association of GH gene polymorphism with growth and semen traits in rabbits
- Study of copulatory behaviour in old male rabbits
- Litter size components traits in two Algerian rabbit lines
- Effect of lighting schedule, intensity, and colour on reproductive performance of rabbit does
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- PublicationEffect of lighting schedule, intensity, and colour on reproductive performance of rabbit does(Universitat Politècnica de València, 2021-03-31) Wu, Yingjie; Zhao, Ang; Qin, Yinghe[EN] In order to establish a lighting regime suitable for rabbit farms in East China, the effects of lighting schedule, intensity and colour on the reproductive performance of rabbit does were evaluated by three experiments, respectively. In experiment 1, does were exposed to different lighting schedules: 16L:8D-continuous, 16L:8D-18d (6 d before artificial insemination (AI) to 12 d post-AI), 16L:8D-6d (6 d before AI to the day of AI) and 12L:12D-continuous. In experiment 2, does were exposed to different light intensities: 40 lx, 60 lx, 80 lx and 120 lx. In experiment 3, does were exposed to different light colours: white, yellow, blue and red. For all experiments, conception rate, kindling rate and pre-weaning mortality were calculated; litter size at birth, litter weight at birth, litter size at weaning, litter weight at weaning and individual kit weight at weaning were recorded. Results showed that none of the reproductive parameters of does were affected by the application of 16L:8D-18d lighting schedule compared with the continuous 16L:8D group(P>0.05). Moreover, rabbits does exposed to 80 lx light performed as well as those under 120 lx light in conception rate, kindling rate, litter size (total and alive) at birth and litter weight at birth (P>0.05). Furthermore, the exposures of 60 lx and 80 lx light were beneficial for litter weight at weaning. In addition, red light had a positive effect, as it led to a larger litter size and litter weight at weaning and lower pre-weaning mortality than white light (P<0.05). In summary, a 16L:8D photoperiod with 80 lx red light from 6 d before AI to 12 d post-AI is recommended for use in breeding of rabbit does according to our results.
- PublicationLitter size component traits in two Algerian rabbit lines(Universitat Politècnica de València, 2021-03-31) Belabbas, Rafik; García, Maria de la Luz; AinBaziz, Hacina; Berbar, Ali; Argente, Maria José[EN] The aim of this study was to estimate the limiting litter size components in rabbit females from a Synthetic line (n=32) and a Local population (n=34). Ovulation rate, number of implanted and live embryos were counted by laparoscopy at 12 d after mating. Prolificacy (total newborn, number born alive and mortality) and embryonic, foetal and prenatal survival at day of birth of the 3rd gestation were measured. The analysed traits were body weight of the female at mating, ovulation rate, implanted, live and resorbed embryos, embryonic, foetal and prenatal survival, as well as total newborn, number born alive and mortality at birth. Synthetic line females had a higher ovulation rate compared to the Local population (11.03±0.23 vs. 8.41±0.23 corpora lutea; P<0.0001). Synthetic line displayed a higher number of implanted embryos (10.00±0.25 vs. 7.85±0.25 embryos; P<0.0001). No difference was found between groups for number of resorbed embryos. Similar embryonic, foetal and prenatal survival rates were reported between the Synthetic line and the Local population. Additionally, total newborn was higher in the Synthetic line than in the Local population (+1.46 kits; P<0.05). A principal components analysis was performed. The first four principal components (PC) explained more than 90% of the total variation in both lines. Total newborn, number born alive and live embryos were the main variables defining the 1st PC. Resorbed embryos and foetal survival were located in the 2nd PC. Ovulation rate and embryonic survival were the predominant variables defining the 3rd PC. The body weight of females was located in the 4th PC. The phenotypic correlation between total newborn and its components were high and positive in both lines, except for ovulation rate and total newborn, where it was moderate in Synthetic line. In conclusion, the females from Synthetic line have a higher total newborn than those from Local population, as a consequence of a higher number of released oocytes and embryos that successfully reach implantation. However, a higher uterine crowding in Synthetic line seems to limit survival of foetuses that reach term of gestation, while ovulation rate is the principal limiting factor of total newborn in Local population.
- PublicationStudy of copulatory behaviour in old male rabbits(Universitat Politècnica de València, 2021-03-31) Jiménez, Pedro; Cuamatzi, Evelia; González-Mariscal, Gabriela; Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México[EN] Male rabbit sexual behaviour consists of a single mount followed immediately by ejaculation. In young bucks this pattern changes gradually as they reach sexual satiety in a day and sexual exhaustion after several daily tests. Little is known about the characteristics of sexual behaviour in old rabbits (aged 48-54 mo) within a day and across daily tests leading to sexual exhaustion. By using sexually receptive(young) females, changed within a session to maximise copulation, we found that: a) the inter-ejaculatory interval increased between the first and last days of testing; b) test duration was 3.1 h on day 1 and 0.5 h on day 15; c) the “miss rate” (i.e., mounts not accompanied by ejaculation) significantly increased from the first to the last day of testing, regardless of when this occurred in each individual buck; d) the total number of ejaculations displayed in a session significantly decreased between the first and the last day of testing in all males; e) scent-marking (“chinning”) frequency significantly decreased after copulation to satiety, relative to that quantified at baseline, and was restored the following day. Compared with young bucks our results indicate quantitative, rather than qualitative, differences in sexual behaviour associated with age in rabbits. Specifically, on day 1 old bucks spent a shorter time engaged in copulation and displayed a lower number of ejaculations before reaching satiety than young males. In contrast, the interval between ejaculatory events and the “miss rate” increased across test days in both old and young rabbits. These results merit investigating the neuroendocrine mechanisms underlying the display of such an active sexual behaviour by old rabbit bucks.
- PublicationAssociation of GH gene polymorphism with growth and semen traits in rabbits(Universitat Politècnica de València, 2021-03-31) Khalil, Maher Hasab El-Nabi; Zaghloul, Abdelfatah R.; Iraqi, Mahmoud M.; El Nagar, Ayman G.; Ramadan, Sherif I.[EN] Although growth hormone (GH) gene mutations are described in several species, the studies concerning their variabilities and associations with economic traits in rabbits are scarce, particularly associations with semen traits. A total of 149 rabbit bucks from five populations (V-line=36, Moshtohor line=28, APRI line=42, cross ½A½M=23, and Gabali=20) were used in the present study to identify polymorphism of c.-78 C>T single nucleotide polymorphism (SNP) of GH gene among these populations and to investigate the association of GH gene polymorphism with body weight (BW), daily weight gain (DG) and semen traits. DNA was extracted from blood samples for genotyping of c.-78 C>T SNP of GH gene based on polymerase chain reaction with the restriction fragment length polymorphism (PCR-RFLP) technique. The genetic diversity of SNP C>T of GH gene was assessed in terms of genotypic and allelic frequencies, effective number of alleles (Ne), observed (Ho) and expected (He) heterozygosity, Hardy-Weinberg equilibrium (HWE), reduction in heterozygosity due to inbreeding (FIS) and polymorphism information content (PIC). Three genotypes of TT, CC and TC of PCR product of 231 bp of GH gene were detected and all the populations were in HWE in terms of GH gene. The highest Ne was obtained for the Moshtohor line (1.978), while the lowest allelic numbers were obtained for V-line (1.715) and Gabali breed (1.800). The highest genotype frequency of GH gene was 0.48 in TT genotype of V-line, 0.21 in CC genotype of Moshtohor line, 0.67 and 0.56 in TC genotype of ½A½M and Gabali rabbits (P<0.05). The highest frequency for C allele was recorded by Moshtohor line (0.45) and the lowest frequency by Gabali (0.32). The genetic diversity scores for GH gene were intermediate (Ho=0.551, He=0.471, PIC=0.358). The values of Ho ranged from 0.444 in V-line to 0.667 in ½A½M cross, while the values of He were 0.425 in V-line and 0.508 in Moshtohor line. The values of PIC were moderate and ranged from 0.332 in V-line to 0.375 in M-line. The highest FIS was observed in Moshtohor line (0.042) and the lowest value was observed in ½A½M cross (–0.413). The CT genotype of GH gene showed the highest and significant values for body weights at 4, 8, 10 and 12 wk (542, 1131, 1465 and 1861 g) and daily gains at intervals of 4-6 and 8-10 wk (23.1 and 26.5 g). Additionally, the CT genotype recorded the highest and significant values for volume of ejaculate (1.1 mL), sperm motility (57.6%), live sperm (85.6%), normal sperm (93.1%) and sperm concentration in semen (611×106/mL), along with the lowest and significant values for dead sperms (14.4%) and abnormal sperms (6.9%).
- PublicationIdentification of nucleotide variation of growth hormone gene in rabbit populations reared in Bulgaria(Universitat Politècnica de València, 2021-03-31) Gencheva, Deyana Gencheva; Koynarski, Tsvetoslav V.; Dafova, Vanya; Tanchev, Svetlin G.[EN] Five rabbit populations of New Zealand White (NZW), Californian (CAL), crossbred NZW×GW and two generations of the synthetic population – SPF1 and SPF2 reared in Bulgaria were included in the present study with the aim of detecting the genetic variability of the growth hormone encoding gene (GH) via polymerase chain reaction with the restriction fragment length polymorphism analysis and direct sequencing. The targeted region of the rabbit GH gene was amplified and a fragment of a total of 231 bp was obtained in all studied populations. Allele identification was determined after enzymatic digestion, where two fragments of 62 and 169 bp correspond to allele C and an undigested fragment of 231 bp corresponds to allele T. Two additional bands of 107 and 124 bp evidenced A/G genetic polymorphism in the rabbit GH gene. Thirtyeight percent of the studied rabbits were carriers of the double mutation (C/T+A/G) in the same locus as the studied GH gene. The sequence analysis revealed two nucleotide substitutions – g.111C>T and g.156A>G in the non-coding region between the regulatory TATA box and 5’ UTR region, and a novel g.255G>A genetic variant in intron 1 of GH gene. The A>G transition was most frequent (40.57%), compared to the other ones, G>A (28.57%) and C>T (10.80%), respectively. The most frequent genotype in the NZW population was homozygous TT (0.93), with a prevalence of the T allele (0.97) over allele C (0.03) for g.111C>T SNP site. The distribution of the allele and genotype frequencies at the sites g.156A>G and g.255G>A in this rabbit group was identical, with the highest value of 0.93 for alleles A and G, respectively. The rabbit populations CAL and NZW×GW showed equal frequencies of the prevalent T allele (0.83) and for homozygous TT genotype (0.67) according to g.111C>T SNP. The highest values were obtained for the allele А (0.83) and for homozygous AA genotype (0.67) at c.33A>G SNP in these rabbit groups. The highest values (0.67, 0.60 and 0.80) for the heterozygous genotypes at g.111C>T, g.156A>G and g.255G>A SNPs, respectively, were detected among the SPF2 rabbit population, compared to the both homozygous genotypes. The results obtained in the present research indicates a significant degree of genetic variability of the studied polymorphic GH locus in the SPF2 rabbit group.