Background: Climate change threatens global food security, highlighting the need for adaptive traits in livestock to ensure sustainable production. Rabbits, known for their unique adaptability, require the preservation of genetic diversity to maintain resilience. The decline in genetic specificity among indigenous breeds underscores the urgency of conservation efforts to protect these critical resources. Objectives: This study investigates the genetic structure and diversity of indigenous rabbit populations, emphasizing genetic mapping as essential for sustaining adaptability. The findings aim to guide breeding programs that enhance biodiversity and support agricultural resilience. Materials and Methods: This study analyzed both native and exotic rabbit breeds. Native breeds included Black Baladi (BB), White Baladi (WB), Red Baladi (RB), and Jabali (JAB), while exotic breeds included New Zealand White (NZW), American Rex (AR), and Chinchilla (CH). Fourteen microsatellite loci were genotyped in 526 rabbits across all breeds. Results: A total of 467 alleles were identified, with an overall mean of 5.03. The expected heterozygote frequencies were medium to high. Polymorphism was high in BB, JAB, and NZW, and medium in WB, RB, AR, and CH. FIS and FIT values (−0.044 and 0.156) suggested possible non-intensive inbreeding. FST (0.220) showed breed differentiation and high within-breed variation. The gene flow averaged 1.872, indicating interbreed gene exchange. Neutrality and phylogenetic analyses revealed genetic reshaping; BB, WB, RB, AR, CH, and NZW showed overlap, while JAB retained high specificity. Conclusions: Urgent conservation strategies are essential to preserve native rabbit genetic diversity and unique traits, which are vital for sustaining biodiversity and livestock resilience globally.

A sixteen (16) weeks study was carried out in rabbit unit of the Teaching and Research Farm, Ambrose Alli University, Ekpoma on the effect of breed on body weight, body linear measurements, haematology, serum-biochemicals and hormones of male rabbits. Fifty-four (54) matured male rabbits were allotted into three groups of eighteen (18) each of Chinchilla (CHIN), New Zealand White (NZW) and New Zealand Red (NZR) breeds and were grouped into a completely randomized design (CRD) experiment. Traits measured were body weight (BW), linear body measurements such as body length, breast girth (BG), height at withers (HT), head to shoulder length (HSL), ear length (EL), ear width (EW) and tail length (TL), blood parameters and hormones. The results of this study demonstrated differences in body weight and body length of rabbits in the study population with Chinchilla (2.26 kg and 34.92 cm), New Zealand White (2.21 kg and 35.08 cm) and New Zealand Red (2.20 kg and 34.42 cm). Haematological indices showed significant differences (p<0.05) among breeds where Mean Hemoglobin, Mean Corpuscular Volume (MCV), Mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) values were higher in Chinchilla breed of rabbit followed by New Zealand White and New Zealand Red. The mean values of total protein, albumin, globulin, uric acids, urea, glucose and phosphorus significantly differed (p<0.05) among breeds with New Zealand Red having higher values followed by Chinchilla and New Zealand White breeds. The results indicate that morphometric traits play a crucial role in selecting rabbits for genetic improvement and predicting market live weight. Also, haematology, serum-biochemical and hormones data were comparable to those described in rabbits and could be used in the classification of rabbits into genetic groups and which could be utilized in crossbreeding programmes to produce crossbreds that are highly productive and adapted to the environment.

The study was conducted to evaluate sire’s strain influence on livability and productivity traits using four rabbit strains; the New Zealand White (NZW), the Chinchilla (CHL), New Zealand Red (NZR) and the FCEABK-α (K-α); a newly developed rabbit strains through di-allele crossbreeding experiment that generated 16 genotypes involving 4 straight bred and 12 crossbreds respectively. The performance of these rabbit strains was monitored to evaluate sire’s strain effect on livability, growth traits and mortality at birth, pre-weaning (21 days), weaning (42 days) and post-weaning age of 84 days respectively. The results indicated that kindling to weaning livability and growth traits varied among the rabbit genetic groups due to differences in their genetic makeup. Chinchilla and K-α improved strain and their crosses performed better relative to other strains studied due to heterotic effect. Recommendations were therefore made that variations that existed in this rabbit population should be thoroughly exploited through crossbreeding and selection programmes. This is desirable in order to take advantage of heterosis in enhancing numerical doe’s reproductive efficiency. The study therefore underscored the importance of sire’s strain influence on livability and growth traits in rabbits, which is a better tool of improving animal agriculture for economic development in Nigeria.

Rabbit production has the potential to help alleviate poverty levels through job creation, income from the sales of rabbits and their products, and a supply of nutritional food, given its urban and peri-urban functionality. However, not much is known about rabbit production and productivity in Zambia. This study was a rapid survey which was intended to document rabbit production systems, management practices, and provide estimates of rabbit productivity in Lusaka, Zambia. Three production systems (extensive, semi-intensive, and intensive) were determined given the following criteria: breeds and number reared, housing provided, feed supplied, management practices and marketing of rabbits and by-products. Most producers practiced an extensive production system, rearing few local and crossbred rabbits which fed mostly on vegetables, and their housing was made of locally available wood materials and or on deep litter. The intensive production system, however, involved purebreds such as New Zealand White (NZW), Chinchilla (CH), California White (CA), Dutch (DU) and Flemish Giant (FG) and their crosses, with numbers ranging between 50 and 100 breeding animals raised in individual metal , cages, fed hay and pelleted concentrate feed. Mortality was lower given the conducive environment and high management practices that reduced contact with faecal droppings and allowed urine to be collected for sale. The semi-intensive production system lies in the middle and is pivotal to improving productivity in the rabbit industry. Mean performances reported were litter size at birth (3.3, 5.2, 6.4), litter weight at birth (105g, 225g, 410g), litter size at weaning (1.9, 4.1, 5.7), litter weaning weight (650g, 1955g, 3256g) and average mature weight (1510g, 2120g, 2825g) for the extensive, semi-intensive and intensive production systems accordingly. The two major challenges were the limited source of breeding animals, which predisposes the sector to a high level of inbreeding and inadequate veterinary care, leading to a high mortality of over 30 per cent. The government is encouraged to develop a national rabbit development programme that will address the above-mentioned challenges.

This study aimed to determine the association between body weight and linear body parameters in rabbits. A total of 93 kittens generated from crosses of New Zealand White (NZW) x NZW, Chinchilla (CHA) x CHA, NZW x CHA, and CHA x NZW genotypes of rabbit in a nested classification of a Completely Randomized Design were used for this study. Data on body circumference weight (BW) and linear body parameters namely, body length (BL), ear length (EL), heart girth (HG), head-to-shoulder (HS), length of hind limb (LHB), length of forelimb (LFB), tail length (TL) and thigh girth (TG) were taken bi-weekly from weeks 2 to 12. The regression procedure used was a stepwise multiple regression using the backward elimination method. The body weight was regressed on linear body parameters using the stepwise multiple regression procedure in SPSS software. The result showed that the regressions of body weight on linear body parameters are all positive and highly significant (p<0.01; 0.05) except for CHA x CHA in week 2. The values of the coefficient of determination (R2) ranged from 26 - 91% in NZW x NZW, 85 - 98% in NZW x CHA, 1 - 88% in CHA x CHA, and 92 - 99% in CHA x NZW. CHA x NZW had the highest R2 value of 94, 99, 94, 97, and 96% in weeks 2, 4, 6, 8 and 12, respectively. NZW x CHA also had a similar R2 value of 94, 96, and 98% in weeks 2, 8 and 10, respectively. For predicting body weight at weeks 2 and 4, LFB and TG were good predictors of body weight for NZW x NZW mating type while at weeks 6 and 10, LFB was a good predictor of body weight. Also, BL and HS proved to be the best predictors of body weight for NZW x CHA mating type. For CHA x CHA, HG and TG were good predictors of body weight while in CHA x NZW, BL was a good predictor of body weight at these periods except for weeks 10 and 12. This suggests that body weight increases with an increase in linear body measurements. Except CHA x CHA in weeks 2 and 12, all the multiple regression equations were significant; all the parameters had R2 values above 60% which shows that the linear model was a perfect fit. Hence, BL can be predicted with accuracy using CHA x NZW cross to facilitate the selection of rabbits for body weight-related purposes.

Thirty-two (32) rabbit bucks of 15-16 weeks (105-112 days) of age comprising of 10 bucks of New Zealand white (NZ), 11 bucks of Chinchilla (CH), and 11 bucks of Dutch (DH) breed with an average weight of 1266 g were used and the experiment lasted for 56 days with each rabbit in a pen. The study to determine relationships amongst carcass traits in some breeds of domestic rabbit (Oryctolagus cuniculus) bucks. All the parameters were weighed in grams with a digital weighing scale while the dressing percentage was calculated. The carcass traits taken were heart, liver, kidney, caecum, lungs, stomach, intestine, live weight, slaughtered weight, dressing weight, fore limb, thoracic cage, loin, skin, head, shank, hind limb, testis, body weight, dressing per cent. The degree of relationships amongst the carcass traits was determined using the Pearson Correlation Coefficient Procedure of SAS. There were several relationships with correlation coefficients ranging from high to low and positively and negatively correlated. The results obtained for relative organs gave positive and significantly (p<0.05) high correlation coefficients between heart and liver (r=0.663) and between intestine and stomach (r=0.570). There was no significant (p>0.05) difference amongst other relative organs but with positive correlation coefficients except between liver and lungs, kidney and caecum, caecum and lungs, caecum and intestine, lungs and stomach, lungs and intestine. For the other carcass traits (live weight, slaughtered weight, dressing weight, fore limb, thoracic cage, loin, skin, head, shank, hind limb, testis, body weight, and dressing per cent), the highest and positive correlation coefficient was obtained between live weight and slaughtered weight (r=0.992), and the least was between shank and testis (r=0.025). It also revealed that live weight had a highly significant (p<0.01) effect on slaughtered weight, dressing weight, fore limb thoracic cage, loin, skin, and hind limb. Therefore, selection for improvement should be carried out on carcass traits with high and positive correlation. More research should be conducted on relationships between carcass traits of domestic rabbit bucks of different breeds and ages.

A study was conducted to estimate the diversity that exists among three rabbit populations adapted to the South-Eastern part of Nigeria. Blood samples were collected from 75 matured, mixed-sex, and unrelated three rabbit breeds selected across the zone. Eight microsatellites (Sol30, Sol33, and Sol44, Sat3, Sat7, Sat8, Sat12, and INRA) markers were used for the study. These microsatellites were uniformly distributed among rabbit genomes for genotyping. Subsequently, genetic variability within and between breeds was calculated. Allelic frequencies and Hardy-Weinberg equilibriums as well as Analysis of Molecular Variance, were also estimated using GenAlEX 6.41 software. Discriminant Analysis of Principal Components (DAPC) for the population structure of the rabbit breeds was performed in R v.3.5.0 using the R package adegenet. All the 8 loci amplified in this study were found to be 100% polymorphic, the observed allele sizes and their frequencies for the microsatellite markers in every three breeds showed that the highest frequency was 0.330 for the allele with the size of 470bp at Sol33 locus in New Zealand White (NZW) rabbits. The Nei’s genetic identities and distances between Chinchilla (CHI) and Dutch (DUT), CHI and NZW, DUT and NZW obtained in this study were [0.173, 0.185, and 0.189] and [1.753, 1.689, and 1.666] respectively. The dendrogram and biplot revealed that the three breeds were identified at two separate clusters. In addition, the admixture level of an individual rabbit among the three breeds indicated that the breeds were not pure and also the existence of more polymorphism within the breed than among the breed diversity.

BackgroundThe study evaluated the growth performance, haemabiochemical and antioxidant profile of two breeds of rabbits fed diets containing varying levels of Rhizopus stolonifer fermented cocoa pod husk meal (FCPHM). Cocoa pod husk meal was taken through solid-state fermentation for a period of 2 weeks using Rhizopus stolonifer as its starter culture. One hundred and eighty, 5-week-old unsexed weaned rabbits 90 New Zealand white (NZW) and 90 Chinchilla (CHL) were randomly allocated into three dietary treatments, Diets I, II and III (0%, 12.5 and 25%FCPHM, respectively), and were arranged in a 2 × 3 factorial design (2 breeds and 3 diets) of a randomized block design.ResultsThe study showed that the breed effect and dietary treatment were significant (p < 0.01) for total weight gain and feed conversion ratio with NZW breed fed 12.5% FCPHM having higher values than CHL breed. Serum total protein concentration was significantly (p < 0.05) influenced by the dietary treatment, while alanine aminotransferase, globulin and total protein concentrations were significantly (p < 0.01) affected by the breed effect. The interactive effect of breed and dietary treatment was only significant (p < 0.05) for serum albumin concentration. Malondialdehyde concentration was significantly influenced by both dietary treatments (p < 0.05) and breed (p < 0.001) factors.ConclusionIt was observed that CHL rabbits were more predisposed to stress than the NZW rabbits as indicated by the lipid peroxidation values, and according to this present finding, 12.5% FCPHM is recommended as active feed ingredient in rabbit diets.

General Combining Ability (GCA) and Specific Combining Ability (SCA) were used to determine the influence of additive and non-additive gene effects on growth parameters, using 2 kits produced in full diallel crosses involving three breeds of rabbits namely, New Zealand White (NZW), Dutch (DT) and Chinchilla (CH). GCA was significant (P&lt;0.05) for four out of the twelve traits studied, namely Body length (BL), Heart girth (HG), Ear length (EL) and Tail Length (TL). GCA values ranged from-12.594 for body weight (BWT) to 0.041 for the length of the hind limb (LHL) for NZW, -3.836 for BWT 10 0.123 for Head Circumference (HC) for DT and -0.035 for Head-to-shoulder (HS) and 16.431 for BWT for Chinchilla. SCA was significant (P&lt;0.05) for HS only. SCA estimates ranged from -0.016 (BWT) to 0.187 (HG), 1.018 (BL) to 10.22 (BWT) and -17.09 (LHL) to 7.354 (BWT). for NZW x DT, NZW x CH and DTX CH crosses, respectively. The significant GCH observed in the four growth parameters indicates that genes governing them aci mainly additively. This implies that they may be genetically improved by selection and pure breeding. Significant SCA for HS is an indication that genes governing this character impart non-additive effects, suggesting that improvement could be brought about by exploiting crossbreeding and by improving the environment.

The study was conducted to evaluate reproductive, growth and carcass traits of two breeds of rabbit and their reciprocal crosses. Two purebred Chinchilla (CHA) and New Zealand White (NZW) and their reciprocal crossing; CHA sire x NZW dam (CHA x NZW) and NZW sire x CHA dam (NZW X CHA) were used in the study. Four genotypes “CHA x CHA, NZW x NZW, CHA x NZW and NZW x CHA” were generated to obtain one hundred and twenty-six (126) kittens. The growth traits studied was body weight (BWT) while reproductive traits studied were gestation length (GL), litter size at birth (LSB), litter size at weaning (LSW), average birth weight (ABWT), average weaning weight (AWWT) and percent mortality (% mortality). The carcass traits evaluated were dressed weight, dressing percentage, weights of liver, heart, lungs, kidney, foreleg, thoracic, loin, hind leg and skin. The data obtained were subjected to analysis of variance and significant means were separated using Duncan new multiple range test. The results indicated that genetic group had significant (p&lt;0.05) influenced on growth, reproductive and carcass traits performances evaluated. The NZW x CHA genetic group had significantly (p&lt;0.05) heavier body weight than the other three genetic groups CHA x CHA, NZW x NZW and CHA x NZW in both the pre-weaning and post-weaning phases of growth. Similar trends were observed for reproductive and some carcass (dress weight, fore leg, thoracic, loin, hind leg and skin) trait performances; the NZW x CH genetic group was superior to every other group. However, percentage mortality was highest in NZW x NZW (50.28±5.78) and lowest in NZW x CHA (5.71±8.69). It was concluded that NZW x CHA had the best performance in most of the traits measured (growth, reproductive and carcass traits) in the study area and therefore using NZW males to cross with CHA females is recommended in the study area to produce rabbits with better performances in term of reproduction, growth and carcass.

Sick chinchillas languish at farms that supply U.S. researchers

The objective of this study was to differentiate between five rabbit breeds at four microsatellite loci on autosomal chromosomes 5, 7 and 19, and to assess the association between detected microsatellite alleles and some economical traits. The breeds were Baladi White (BWH) and Baladi Red (BR) as native Egyptian breeds, and New Zealand White (NZW), American Rex (AR) and Chinchilla (CH) as exogenous breeds. Genomic DNA was extracted from nine individuals/breed, and screened by four pairs of microsatellite markers (Sat5, D7Utr4A, D7Utr4B and D19Utr4B). A total of 26 alleles was detected, with an average of 6.5 alleles per locus. The within-breed genomic variability was in general high, and was not significantly differed between breeds. The expected heterozygosity was also high and ranged from 0.769 in NZW to 0.826 in CH, with no significant differences between the breeds. The average polymorphism information content (PIC) varied from 0.286 in BWH to 0.593 in CH. The genetic distance indices revealed close genetic relationship between BWH and CH and averaged 2.629, however the genetic distance between AR and NZW averaged 3.355. Many alleles were found to associate many growth and reproduction traits. D7utr4A`4 showed significant association with body weight and chest circumference at 8 weeks of age and body length at 8 and 10 weeks of age. The microsatellite locus D7Utr4B on chromosome 7 showed significant association with parity.

The ovary is a structurally dynamic organ that alters with age. Modifications in the paracrine status influence the capacity of aging oocytes to develop normal embryos. Despite the importance of understanding the cellular and molecular mechanism involved in the process of ovarian aging, histological changes remain poorly understood. Correlating the process of folliculogenesis and somatic cell function during ovarian aging is essential to explain the reproductive decline of aged mammalian species, including humans. Here, we performed a morphological and immunohistological study on the ovaries of chinchilla rabbits that varied in age from one to 34-months. The spatiotemporal expression of the cholesterol side-chain cleavage cytochrome P450scc (CYP11A) and the smooth muscle actin (SMA) were analyzed. A significant histological rearrangement of immunodetected cells in theca interna, theca externa and the interstitial tissue around the follicles occurred. The expression of CYP11A1 decreased considerably in antral follicles of aging ovaries. Moreover, we found that the secondary interstitial gland developed extensively, and a remarkable rearrangement of the surface epithelium occurred in aging ovaries. In contrast to ovaries during the reproductive period, the immunohistological changes demonstrate that the interstitial gland became the most abundant tissue during the aging of ovaries. Thus, the current study provides new data for understanding the alteration of somatic cell function in elderly ovaries and how this affects their declined fertility.

BackgroundRabbit breeding with high performance imported ones would be of benefit for genetic diversity and improvement of performance in domestic rabbit breeds. The rearing of more productive rabbit breeds could be pathway to improve the productivity and reduce the production cost. Maternal nutritional status exert a great influence on reproductive functions of does, which may expand from conception, through gestation and parturition and development of kits to puberty.MethodsFour breeds of rabbit were evaluated for their parturition, weaning and pubertal differences among the rabbit population in Ibadan, Nigeria. The breed consist of Fauve De Bourgogne (FDB), Chinchilla (CHA), British Spot (BS) and New Zealand White (NZW) rabbits. A total of 60 bucks and 360 does consisting of 15 bucks and 90 does per breed were mated in 6 mating cycles, three each of natural mating and artificial insemination. All does were synchronized for estrus with 20 IU pregnant mare serum gonadotropin 48 h prior to mating. The does after parturition were assessed for milk yield (g) and kit survival rate (%) till weaning, weight changes of kits from birth to puberty. At puberty, the pubertal age (days) and weight (g) of the offspring were assessed.ResultResults obtained reveals that British Spot doe had highest milk yield among the breeds which significantly increased growth of kit and weight at weaning in British Spot rabbits. Survival rates of Chinchilla kits were significantly (p < 0.05) higher than Fauve de Bourgogne, British Spot and New Zealand White kits. Puberty attainment of the rabbits indicates that British spot does and Fauve de Bourgogne bucks are early maturing.ConclusionChinchilla shows high kit survivability and British spot has highest milk yield among the four breeds of rabbit.

Intravitreal (IVT) injection has become one of the most commonly performed ophthalmologic procedures. We investigated the changes in retinal function and proteomics in rabbits receiving IVT injection of PBS to evaluate the safety of IVT injection. Twenty Chinchilla rabbits were subjected to IVT injection of 50 µL PBS in the right eyes. On days 0, 4, 7 and day 14, the retinas of the rabbits were isolated after routine ophthalmic and electroretinogram examinations. The protein expressions in the retinas were quantified using tandem mass tag (TMT)-labeling coupled with LC-MS/MS, and bioinformatic analysis of the differentially expressed proteins (DEPs) was performed based on KEGG database to identify significantly enriched pathways. Functional network of the significant DEPs was analyzed using STRING. No noticeable fundus or functional changes occurred in the rabbit eyes following IVT injection of PBS. A total of 6042 retinal proteins were identified in the retina following the injection, among which 49 proteins (0.81%) exhibited over 5.0-fold up-regulation or over 80% down- regulation relative to the control. Most of the distinctly up-regulated or down-regulated proteins were associated with the cytoskeleton. Significantly enriched pathways involved focal adhesion, tight junction, riboflavin metabolism, extracellular matrix-receptor interaction and regulation of actin cytoskeleton. Functional network analysis showed that ACTC1 and ISG15 played central roles in the protein interaction networks. IVT PBS injection in rabbits causes alterations in proteins associated with cell adhesion, morphology, migration, differentiation, signal transduction and riboflavin metabolism, but the alterations of the retinal proteins appear not sufficient to cause observable pathology of the retina.

Taking into consideration the growing importance of this species in the field of neurology research, we have aimed to provide extensive data on the gross morphology of the Chinchilla lanigera’s cerebral hemispheres. The data was compared to the general features of the rodent brain extracted from literature. Five bodies of Chinchilla lanigera , three females and two males, all adults were used in order to obtain cerebral samples. Each segment of the cerebral hemispheres was examined macroscopically, both intact and on seriate sections, in order to register it external features, as well as its internal structure. The examination was performed on both fresh samples and after treating them with a buffered solution of formaldehyde. Gross measurements were also performed, but without the intent of statistical processing. The cerebral hemispheres of the Chinchilla are lissencephalic, and decrease in girth in the oral direction, presenting each a triangular surface. The internal optostriate bodies are well developed and clearly differentiated form the cortex, but the individual cerebral nuclei are hard to distinguish macroscopically, visible as a common gray mass. The most prominent inter-hemispherical segment is the corpus callosum, easily underlined by longitudinal sections of the cerebrum, subjacent of the cortex. We have also been able to identify the main ventricular cavities of the cerebrum: the first and second ventricles. The cerebral hemispheres of the Chinchilla retain the main characteristics of the rodent brain. All the common segments were identified and found to closely resemble either the rabbit, or the rat brain, in various proportions.

One hundred and thirty rabbits were used to evaluate the effect of genotype, gestation length, season, parity and sex on growth traits of two breeds of rabbit and their crosses. The rabbit used for the experiment were breeds of the New Zealand White (NZW) and Chinchilla (CH) breed. Six breeding bucks (three/breed) and eighteen breeding does (nine/breed) served as the foundation stock. Traits measured include: body weight (BW), nose to shoulder length (NTS), shoulder to tail length (STL), heart girth (HG), trunk length (TL) and length of ear (LE). Results revealed that, BW of the rabbits were influenced (p&lt;0.05) by genotype, gestation length and season. CH x (CH x NZW) progenies had better BW at 35-d and 49-d of age while NZW x CH progenies had better BW at 21-d of age. Kittens born late (32-34 days) had better BW at 21-d, 35-d and 49-d while kittens kindled during early dry season had better BW at 21-d, 35-d and 49-d. Genotype affected (p&lt;0.05) all the body measurements at 21-d, 35-d and 49-d. Gestation length affected (p&lt;0.05) all the body measurements except for NTS at 21-d and HG at 49-d respectively. Season of birth also influenced (p&lt;0.05) all the body measurements except for LE 21-d. Parity and sex had no effect (p&gt;0.05) on BW, NTS, STL, HG, TL and LE. It was concluded that genotype, gestation length and season influenced BW and body dimensions of the two breeds of rabbit and their crosses while parity and sex had no effect.

Objective To measure the scleral thickness of the rabbit eye at different locations in the globe,providing a theoretical basis for advanced research in transscleral drug delivery.Methods In this experimental study,98 eyes of 49 adult pigmented rabbits were sacrificed after deep anesthesia and the eyeballs were enucleated and fixed in 1％ buffered formaldehyde and 1.25％ glutaraldehyde for a minimum of 36 hours.The eyes were processed for routine paraffin embedding and sectioning.The sagittal sections at the optic nerve level were collected and used for scleral thickness study.The images were acquired at serial locations between the limbus and optic nerve and the thickness was measured with SPOT image software.The data were analyzed with generalized estimating equations (GEE) and Tukey's HSD Post Hoc Test.Results In general,the mean scleral thickness of the inferior eye globe was significantly thinner than that of the superior globe (342.9±91.3 μm versus 400.4±67.6 μm,x2=43.57,P＜0.01,GEE).There were no significant differences in the scleral thickness from the pre-equator vicinity to the posterior pole,with a mean thickness of 366.8±56.3 μm at the superior globe.For the inferior globe,the mean scleral thickness at the pre-equator vicinity and at the equator was similar,340.9±72.5 μm and 340.8±76.3 μm.However,scleral thickness decreased to 293.9±57.4 μm at the post-equator vicinity and to 209.0±51.8 μm at the posterior pole.The thinnest sclera was located immediately around the optic nerve,273.5±90.5 μm for the superior and 187.7±60.1 μm for the inferior,compared to the other locations (P＜0.05,Tukey's HSD Post Hoc Test).Conclusion Rabbit sclera is thinner than human sclera.In the rabbit eye globe,the superior sclera is significantly thicker than the inferior sclera and superior sclera is shorter and more uniform in thickness between the equator and the posterior pole.Scleral thickness has larger variations between the limbus and equator than the variations between the equator and the posterior pole. Key words: Rabbits; Scleral thickness; Transscleral drug delivery

El objetivo fue presentar los valores de 47 caracteres metricos y 20 indices craneales del craneo de 291 chinchillas de granja maduras y comparar estos datos con los determinados sobre 32 craneos de chinchilla obtenidas desde el Museo de Historia Natural de Londres. Se tomaron mediciones de los parametros del viscerocraneo, neurocraneo y de la mandibula. No se observo una distribucion normal de estos rasgos. Se calcularon los valores de los coeficientes de correlacion de Spearman seleccionado. Se encontro que los rasgos craneales de las chinchillas de granja mostraron valores significativamente superiores (P 0,01) en comparacion con los especimenes de museo. El efecto del entorno agricola, en el que las chinchillas de granja se habian mantenido durante muchas generaciones, podria ser una razon probable para estas diferencias.

The effect of Cross breeding and reciprocal crossing on birth, weaning and growth traits of two strains [Chinchilla (CH) and New Zealand white (NZW)] of rabbits aged between 3-4 months were investigated. A total of eighteen (18) does (nine does per strain) and six (6) bucks (three bucks per strain) were used in this study. Three (3) does per strain were assigned to a buck from the opposite strain for mating and the treatment was replicated. The does were mated when they attained the age of 5 months. Birth traits like litter size, litter weight, gestation length, gestation gain, kindling loss and neo-natal mortality were observed. At weaning, litter size, litter weight, litter weight gain, sex ratio and survival rate were monitored. Growth traits like body weight, nose to shoulder length, shoulder to tail length, trunk, ear length and heart girths were monitored at 21, 35 and 49 days. Results obtained showed that Chinchilla (CH) buck crossed with New Zealand white (NZW) does produced offspring with significantly (P< 0.05) better body weight, nose to shoulder length, shoulder to tail length, heart girth, trunk and kindling loss. However, results obtained for neo-natal mortality was better in the offspring from NZW bucks and CH does. It was concluded that progenies from the crosses between CH bucks and NZW does, were better than progenies from the crosses between NZW bucks and CH does.