Comparison of milk production and milk composition for an exotic and a local synthetic rabbit lines

Comparative Analysis of Angora Rabbit Colostrum and Mature Milk Using Quantitative Proteomics

Colostrum intake is a crucial determinant of survival in newborn rabbits. Neonates rely entirely on passive immunity transfer from their mothers while suckling colostrum. The goal of this study was to explore the protein differences of rabbit milk during different lactation periods. Our findings showed that the daily milk yield exhibited an increasing trend from the 2nd to the 21st day of lactation. A data-independent acquisition proteomics approach identified a total of 2011 proteins. Significantly, different abundances were found for 525 proteins in the colostrum and the mature milk samples. Eleven differentially abundant proteins (DAPs) were examined using parallel reaction monitoring, which verified the reliability of the proteomic data. Gene Ontology analysis revealed that these DAPs were primarily associated with glycosyltransferase activity, macromolecule transmembrane transporter activity, and regulation of acute inflammatory response. The dominant metabolic pathways of the DAPs involve the complement and coagulation cascades. A protein-protein interaction analysis identified apolipoprotein B, apolipoprotein A1, triose phosphate isomerase 1, and albumin as the hub proteins responsible for distinguishing differences between biological properties in rabbit colostrum and mature milk. These findings enhance our comprehension of the rabbit milk proteome, particularly in expanding our knowledge regarding the requirements of neonatal rabbits.

Effect of Adding the Antimicrobial L-Carnitine to Growing Rabbits' Drinking Water on Growth Efficiency, Hematological, Biochemical, and Carcass Aspects

The current study was designed to assess the impact of L-carnitine (LC) supplementation in the drinking water of growing Alexandria-line rabbits on performance and physiological parameters. Two hundred eighty-eight 35-day-old rabbits were divided into four groups of twenty-four replicates each (seventy-two rabbits/treatment). The treatment groups were a control group without LC and three groups receiving 0.5, 1, and 1.5 g/L LC in the drinking water intermittently. The results showed that the group receiving 0.5 g LC/L exhibited significant improvements in final body weight, body weight gain, feed conversion ratio, and performance index compared to the other groups. The feed intake remained unaffected except for the 1.5 g LC/L group, which had significantly decreased intake. Hematological parameters improved in all supplemented groups. Compared with those in the control group, the 0.5 g LC/L group showed significant increases in serum total protein and high-density lipoprotein, along with decreased cholesterol and low-density lipoprotein. Compared to other supplemented groups, this group also demonstrated superior carcass traits (carcass, dressing, giblets, and percentage of nonedible parts). In conclusion, intermittent supplementation of LC in the drinking water, particularly at 0.5 g/L twice a week, positively influenced the productivity, hematology, serum lipid profile, and carcass traits of Alexandria-line growing rabbits at 84 days of age.

The Role of PRLR Gene Polymorphisms in Milk Production in European Wild Rabbit (Oryctolagus cuniculus)

One of the problematic points of rabbit breeding is that the nutritional requirements of the kits are not fully satisfied by the does' milk production from the third week of lactation onwards. The prolactin receptor gene has a significant effect on reproductive processes, and its polymorphisms have been associated with milk production in several species (cattle, goats, sheep, and buffalo). The European wild rabbit (Oryctolagus cuniculus), has a more diverse genetic background compared to domesticated lines. In the course of our study, sequencing of the 1210 bp long segment of the PRLR gene promoter region was accomplished. We detected four point mutations (SNP1-407G > A, SNP2-496G > C, SNP3-926T> and SNP4-973A > C) and one microsatellite at position 574. In our population, the four SNPs were segregated into four genotypes: AACCCCCC, GGGGTTAA, AAGGTTAC, and GGGGTCAC. Our results show that the genotype in the homozygous form is associated with higher milk production (1564.7 ± 444.7 g) compared to the other three genotypes (AACCCCCC 1399.1 ± 326.8 g; GTGACCTT 1403.8 ± 517.1 g; GGGGTCAC 1220.0 ± 666.2 g), and the short microsatellite repeat (167 bp) also coincides with significantly higher milk production (1623.8 ± 525.1 g). These results make the marker-assisted selection possible also for domesticated lines.

Mitochondrial D-loop sequences and haplotypes diversity in Egyptian rabbit breeds

Rabbit breeds in Egypt are local and adapted foreign breeds that have been imported since the middle of the last century. Stressful environmental conditions including climatic changes, exposure to diseases and breeding selection have an influence on how gene flow has shaped the genetic diversity of the breeds. Mitochondrial DNA D-loop is a genetic marker used to trace the geographic distribution of genetic variation for the investigation of expansions, migrations and other gene flow patterns. The study aimed to determine the genetic diversity of the mitochondrial DNA D-loop (mtDNA D-loop) in Black Baladi, Red Baladi, Gabali, APRI line and New Zealand breeds to gather the scientific data required to create a proper conservation and sustainable management plan. Blood samples were taken from animals unrelated to each other. A 332-bp of mtDNA D-loop was successfully amplified and alignment sequences were deposited in the GenBank database. The results detected six haplotypes in the five breeds. Haplotype diversity within individual breeds varied from 0 (Red Baladi) to 0.551±0.114 (Gabali). The nucleotide diversity (π) value was relatively low (0.001-0.006), with greater values in APRI and New Zealand. Pairwise distances between breeds yielded varying values ranging from 0 to 0.254, and the values between the Red Baladi and other breeds were comparatively high, with pairwise distances from 0.172 to 0.254. The phylogenetic analysis involved 74 nucleotide sequences of the Egyptian rabbit and thirty-one sequences retrieved from GenBank of the reference samples of different haplogroups. The results of the phylogenetic analysis correlated to the reference mtDNA GenBank database showed that the five Egyptian rabbit breeds were grouped into haplotypes A, B and K. The results of the genetic diversity using mtDNA shed light on the importance of the local breed’s genetic diversity information and revealed unique mtDNA haplotypes, which is an important finding for breeding strategies designed to conserve genetic variants and provide sustainable management.

Hycole Doe Milk Properties and Kit Growth

Simple Summary

The rabbits used on the commercial rabbit farms for the production of rabbit fryers are crosses of synthetic lines, such as Hycole. The maternal rabbit lines are selected not only for high number of kits but also for high production of milk. The goal of the presented study is related to the lack of complex data on the quality of rabbit milk, though this milk determines the nutritional status of kits in the suckling period as well as body weight gains and survival of rabbit kits. There are data on the milk yield of rabbit does and the milk proximal chemical composition, but the hygienic quality of this milk (somatic cell count) and its relationship with milk yield, kits survival, and weight gains is an unanswered question. The presented findings show the significant relationship between litter size, which has a clear effect on the milk production, as well as litter weight. Also shown is that the day of lactation affected the physiochemical traits of rabbit milk.

Abstract

The level of production and the physiochemical traits of rabbit milk affect the growth and the mortality of bunnies during lactation. The goal of the study was to analyze the effect of litter size and day of lactation on the quality traits of rabbit milk, milk production, and associative traits. The study was conducted on 32 Hycole does and their litters. The rabbit milk pH ranged from 6.61 to 7.46. The colostrum was characterized by the highest content of total solids (31.54 and 31.80 g kg⁻¹) and fat content (15.73 and 15.9 g kg⁻¹). The milk from the beginning of the lactation was characterized by the highest level of somatic cell count (SCC) (523.67 and 536.57 10³ mL⁻¹), which gradually decreased to reach the lowest level on days 17 and 21 of lactation. The daily milk production was greater for does nursing 10 kits per litter compared to those nursing eight kits per litter (p < 0.001). The peak of milk production occurred on day 17 postpartum. To conclude, the litter size has a clear effect on milk production as well as litter weight and litter weight gains. It is also important to note that the day of lactation affected the physiochemical traits of rabbit milk.