Kit Weight Research Articles

VARIATION IN LITTER SIZE AND ITS ASSOCIATION WITH PRE-WEANING WEIGHTS OF MONGREL RABBIT KITS REARED IN GUINEA SAVANNAH REGION OF NIGERIA

This work was aimed at investigating the effect of litter size on growth performance of mongrel rabbits reared in the Guinea savannah geo-ecological region of Nigeria. Thirteen mongrel rabbits does and four bucks were used as parents to generate the kits. The research was conducted at the Livestock Teaching and Research farm, Joseph Sarwuan Tarka University, Makurdi, Benue State. Data were collected on birth weights and weekly body weights changes of rabbit kits using sensitive weighing balance. Data were subjected to one-way analysis of variance as implemented in SPSS. Significant disparity (P>0.001) was recorded in birth weight of kits with litter size 5 having higher birth weight than litter sizes 6, 7 and 8. Litter size 6, 7 and 8 had comparable birth weight (P<0.05). Rabbit kits in litter size 5 had significantly (P<0.05) higher body weight at week 1 than those in litter sizes 6, 7 and 8. Rabbit kits in litter size 5 also had significantly (P<0.001) the highest body weight at weeks 2, while kits in litter sizes 6, 7 and 8 had comparable body weight at week 2. Body weights at week 3 were comparable among kits in litter sizes 6, 7 and 8, but lower than that of kits in litter size 5. This trend continued up to week 5 of age. Significantly (P<0.05) positive and moderate correlations were recorded between birth weight and body weights at week 1 to 5. In conclusion, the higher the itter size, the lower the birth weight and pre-weaning weight of mongrel rabbits.

EFFICACY OF SELECTED POLYHERBAL PRODUCTS TO IMPROVE REPRODUCTIVE PERFORMANCE IN RABBIT DOES

The efficacy of selected of Janova® and Exapar® on the reproductive performance of rabbit does was investigated. Forty rabbit does mixed breeds (1.8-2.4 kg body weight) with 0-2 parities were randomized into four treatments (T1-T4) of ten does each, in a Completely Randomized Design (CRD). T1 animals received no herbal supplementation (control); T2 animals were drenched with 0.67 g Janova®/kg body weight (kg/BW); T3 animals were drenched with 0.2 g/kg/BW Exapar®, while the T4 animals were drenched 0.67 g/kg/BW of Janova® + 0.2 g/kg/BW of Exapar®. Data on kindling rate (KR), gestation length (GL), litter size (LSK) and litter weight at kindling (LWK), average kit weight at kindling (AKWK), and sex ratio (SR) were collected. The data collected were statistically analysed using One-way ANOVA of SAS® software, the significant level for the group comparisons was set at p<0.05. Results from the experiment revealed that T1 does had the highest KR of 44%, followed by T2 and T3 does with 33.3% each, while the does in T4 had the least KR of 25%. The GL obtained in the T1 (33.25 ± 0.63d) was significantly higher (p<0.05) than the values obtained in treatments T2, T3 and T4 does with mean GL of 31.33 ± 0.33d, 31.33 ± 0.33d and 30.50 ± 0.50d, respectively. Polyherbal products (Janova® and Exapar®) brought about shortened gestation length in the does supplemented as compared to the control group.

EFFECTS OF GENOTYPE, GESTATION LENGTH AND LITTER SIZE ON THE BIRTH WEIGHT, LITTER WEIGHT, THIRD AND FIFTH WEEK BODY WEIGHT OF CROSSBRED KITS

Future performance of rabbit is hinged on many factors of which the birth weight, gestation length, and the litter size are most important. One hundred cross bred kits from five breeds of rabbits (Dutch- belted (DUC), Rex, Californian white (CAL), New Zealand White (NZW) and locally adapted strain (LOC)) were used to confirm this assumption. The study was carried out at the rabbit unit of the Livestock Farm of Teaching and Research Farm at the Federal University of Technology, Akure. The rabbits were fed ad libitum with grower's mash which was wet with water to avoid dustiness; this was supplemented with forages (Tridax procumbens and Talinium triangulae) in the evening. Individual birth weight, litter weight, litter size and weekly body weight were recorded before meal in the morning. Genotype exerted significant influence (P<0.01) on the individual and litter weight at birth as well as on the body weight of the kits at 21st and 35th days. The kit kindled from mating CALXDUC breeds had the highest mean body weight from birth (91.909.84g) to 35th days (368.2517.36g) while the crosses of DUCXCAL recorded the lowest mean body weight from birth (74.251.78g) to 35 days (332.6012.54g). There were also significant differences (P<0.05) for the individual and litter birth weights, body weights at 21st and 35th days based on the duration of gestation among the does. Does with short gestation length (29 days) had kits with light body weight compared to those with longer periods of gestation (34 days). More so, kits belonging to a large litter size (7) had the light body at as well as and Future performance of rabbit is hinged on many factors of which the birth weight, gestation length, and the litter size are most important. One hundred cross bred kits from five breeds of rabbits (Dutch- belted (DUC), Rex, Californian white (CAL), New Zealand White (NZW) and locally adapted strain (LOC)) were used to confirm this assumption. The study was carried out at the rabbit unit of the Livestock Farm of Teaching and Research Farm at the Federal University of Technology, Akure. The rabbits were fed ad libitum with grower's mash which was wet with water to avoid dustiness; this was supplemented with forages (Tridax procumbens and Talinium triangulae) in the evening. Individual birth weight, litter weight, litter size and weekly body weight were recorded before meal in the morning. Genotype exerted significant influence (P<0.01) on the individual and litter weight at birth as well as on the body weight of the kits at 21st and 35th days. The kit kindled from mating CALXDUC breeds had the highest mean body weight from birth (91.909.84g) to 35th days (368.2517.36g) while the crosses of DUCXCAL recorded the lowest mean body weight from birth (74.251.78g) to 35 days (332.6012.54g). There were also significant differences (P<0.05) for the individual and litter birth weights, body weights at 21st and 35th days based on the duration of gestation among the does. Does with short gestation length (29 days) had kits with light body weight compared to those with longer periods of gestation (34 days). More so, kits belonging to a large litter size (7) had the light body at as well as and day 209.57-3.70g, 319.1119.22g) revealing significant influence (P<0.05) of litter size on the body weight of kits which was different from kits of lesser litter size. Based on the results of the experiment carried out, a crossbreeding involving breeds of sires and does is recommended to produce offspring with better performances. 209.57-3.70g, 319.1119.22g) revealing significant influence (P<0.05) of litter size on the body weight of kits which was different from kits of lesser litter size. Based on the results of the experiment carried out, a crossbreeding involving breeds of sires and does is recommended to produce offspring with better performances.

Potential use of dimethyl sulfoxide (DMSO) in artificial insemination of rabbits

The aim of this work was to analyse the effect of incubation dimethyl sulfoxide (DMSO) with insemination dose (ID) on reproduction parameters (kindling rate, number of live and still-born kits and birth weight of kits). The experiments were carried out under the conditions of two rabbit breeds. An ejaculate was diluted to concentration of 40 to 50 million/0.5 ml/ID. DMSO was added to the ID in concentration of 0.5 M DMSO. Control ID did not contain any DMSO. Kindling rates obtained from 2 different breeds (P1, P2) showed minor improvement (+4.36% P1; +4.06% P2) between the monitored groups of females, however without statistically significant differences. Number of live born kits in litter obtained from breeds P1 and P2 showed minor improvement (+0.61 pcs P1; +0.13 pcs P2) compared to the control groups (p>0.05). The weight of live born kits was higher in experimental groups (+3.85 g P1 = p≤0.001; +1.18 g P2 = p>0.05) compared to the control groups. Monitoring of sperm quality indicators (1, 3 and 6 hours incubation) in vitro conditions (CASA – Computer Assisted Semen Analyzer) showed the best results in the control group of non-affected DMSO. The data obtained from our experiments suggest the possitive effects of DMSO incubation on reproduction parameters especially in vivo.

Genetic and Phenotypic Parameters of Rabbit Individual Body Weight in the Preweaning Period.

The preweaning weight of kits has been related to their mortality during the suckling period. Selecting rabbit kits for individual body weight in the first days of life could be interesting; however, better knowledge of body weight's heritability during the preweaning period is necessary to determine the opportune moment for selection. A total of 1696 growth records of kits from 81 females of the ITLEV2006 synthetic line were analysed in order to estimate the genetic and non-genetic parameters for individual body weight at birth as well as at 5, 7, 14, 21, 28, and 35 days of age. The estimates of heritability (h2) for individual weight were between low (0.11 at birth, 0.16 at 5 days, and 0.17 at 7 days) and moderate (0.21, 0.21, 0.24, and 0.21 at 14, 21, 28, and 35 days, respectively). Weight at birth showed a strong and positive genetic correlation with weight at 5 days (+0.79) and 7 days of age (+0.78), but the correlation was low for the rest of the weight measurements (+0.41, +0.49, +0.54, and +0.54 with weight at 14, 21, 28, and 35 days, respectively). Weight at 5 days and 7 days displayed strong and positive genetic correlations with the rest of the weight measurements (higher than +0.83). The values of the common litter effect (c2) were high, and they increased with age from 0.43 at birth to 0.66 at 35 days of age. The values of the maternal permanent effect (p2) were low compared to those of the common litter effect (c2), varying between 0.04 and 0.11. In conclusion, opting to select for body weight at 5 or 7 days of age would yield a greater response compared to selecting for birth weight. This approach would indirectly increase the kits' weight at birth and at weaning, thereby reducing preweaning losses.

Growth, survival rate of New Zealand White, Dutch Rabbit and their crosses

Abstract. The aim of the study was to assess survival rate of crossbred New Zealand White and Dutch rabbit breed. A total of 16 mature rabbits of seven to nine months old, New Zealand White and Dutch were used for the study. Data obtained were subjected to analysis of variance ANOVA using SAS. The reproductive traits studied were litter size, litter birth weight, mean kit weight. The growth traits were: body weight, body length, ear length, chest circumference, hind limbs, thigh length, nose to shoulder and thigh circumference. The reproductive traits were significantly (P<0.05) affected by genetic group Pure and crosses. New Zealand White observed high litter size and litter birth weight at first, seventh, 14th and 21st day. Purebred Dutch had significant (P<0.05) high values for growth traits. The body weight 478.73±18.10, body length 33.12±0.42, ear length 9.10±0.09, chest circumference 18.24±0.45 and hind limbs 19.51±0.33 were significantly (P<0.05) high in crosses of Dutch x New Zealand White. Pre-weaning mortality and survival rate at weaning were 22.22% and 77.77% high in New Zealand White; 14.28% and 85.71% in Dutch and DUC x NZW; and 9.09% and 90.90% in NZW x DUC. In conclusion, New Zealand White x Dutch crosses demonstrated high survival rate and low pre-weaning mortality.

Effect of vitamin E, D-limonene, and their combination on nulliparous rabbit reproductive performance

Oxidative status is important in reproductive performance and using two natural antioxidants is more beneficial than one in nulliparous rabbits. The goal, effect of vitamin E (VitE), D‐limonene (DL), and VitE+DL on maternal LBW (MLBW), conception (CR), pregnancy (PR), and kindling rates (KR), gestation length (GL), total litter size at birth (TLSB) and weaning (TLSW), live kits at birth (LKB) and weaning (LKW), dead kits at birth (DKB) and weaning (DKW), kits mortality rate at weaning (KMRW), Kit weight at birth (KWB) and weaning (KWW), total kit weight at birth (TKWB) and weaning (TKWW), and concentrations of progesterone (P4) and Malondialdehyde (MDA), during first two pregnancies. A total of 24 healthy female WNZ rabbits were randomly selected and assigned into four groups (6/each). Control (animals injected with 1.0 mL propylene glycol), VitE (60 mg IM injection/animal, 2X/week pre-mating and 3X post-mating until mid-pregnancy, DL (20 mg IM injection/animal, 2X/week pre-mating and 1X at mating, and VitE+DL (IM injection/animal with the same doses and times applied in VitE and DL groups. All animals were treated during 1st pregnancy only. The results confirmed that animals treated with VitE+DL gained significant maternal LBW in 1st pregnancy, reduced dead kit number at birth and kit mortality rate at weaning, increased live kits and total kit weight at birth and weaning in the two pregnancies, and also increased significantly kit weight at birth and weaning in the treatments than controls in the two pregnancies, and DL was greater in 1st pregnancy. Progesterone concentrations in mid-pregnancy rose significantly in VitE+DL during 1st pregnancy and DL in 2nd pregnancy. Malondialdehyde concentrations dropped significantly in VitE and VitE+DL in mid-pregnancy in the two pregnancies. Eventually, the integration of VitE and DL displayed their unique properties for improving productive and reproductive performance in nulliparous rabbits.

Effect of group size and escape enrichment on reproductive performance of breeding does in part-time group housing

Societal demands for group housing of social farm animals such as rabbits are increasing due to animal welfare concerns. When breeding does are housed in groups, maternal protective behaviour negatively affects the reproductive performance of the does. In part-time group housing, does are housed in single-litter cages starting shortly before parturition until the first part of lactation and then group housed for the second part after their protective behaviour has diminished and the kits are more resilient. The aim of this study was to evaluate the reproductive performance of breeding does in a part-time group housing system with provision of escape enrichment and different group size (and concomitant different stocking density, as pen size remained unchanged). For each of the four consecutive reproductive cycles, 42 does with their kits switched at 22 d post-partum (pp) from single-litter to group housing for a total period of 13 d in pens of 200×102 cm by removing walls between four adjacent single-litter cages. Newly created group pens (N =12 pens per treatment) varied in group size, stocking density and enrichment: groups of either three or four does were divided over same-size pens with or without escape enrichment (2×2 factorial design). The escape enrichment was comprised of two sets of PVC pipes and two extra elevated platforms. Does were weighed and kits counted at parturition, after which kits were cross-fostered. Kits were counted and weighed again 22 and 35 d pp. Results for mean doe fertility (90.0%), number of kits (9.1 kits/litter) and kit weight (1037.3 g/kit) at weaning were comparable with professional farms using single-litter cages. No significant effects of group size and escape enrichment were found for any of the reproductive parameters. While housed in group, seven does were removed from the experiment, from which four does were severely injured. Post-grouping kit mortality was rather low (6.7%), but three kits were euthanised due to severe injuries. In conclusion, provision of escape enrichment and altered group size (and stocking density) had no profound effect on the reproductive performance of part-time group housed does.

Prenatal factors affecting the probability of survival between birth and weaning in rabbits

The aim of this study was to analyse the relationships between kit birth weight and litter size with kit survival from birth to weaning, and to estimate the effects of place of birth, nest quality, cannibalism, lactation, parity order, season and sex. A total of 1696 kits from 82 females of the ITLEV2006 synthetic line were used in this study. A logistic regression was performed. Kit birth weight was directly related to the probability of the kit’s survival from birth to weaning, and increasing birth weight by one gram increased the likelihood of kit survival by 8% to 10% (P<0.001). In line with the decrease in birth weight of kits as the number of kits at birth increases, litter size showed a negative relationship to the probability of survival from birth to weaning, and increasing the litter by one kit at birth decreased the probability of survival of the kits by 5% to 9% (P<0.05). Regarding effects, cannibalism events in the litter decreased the probability of survival of the kits in the first week of life (P<0.01). Being born in the cage decreased the probability of survival of the kits from birth to weaning, and kits born outside the nest had a lower chance of survival than those born inside the nest (P<0.01). The order of parturition had a positive effect on probability of survival of the kits from 5 days of age to weaning (P<0.05). Female kits had a lower chance of survival than male kits, but only until 5 days of age (P<0.01). The lactation status displayed a negative effect on the probability of survival of the kits in the first week of life, and kits gestated in lactating females had a lower chance of survival than those gestated in non-lactating females (P<0.05). In conclusion, the probability of kit survival in the first days after parturition was affected mainly by its weight at birth, litter size, cannibalism events, place of birth of kit, parity order, sex and lactation status, while the probability of kit survival at weaning was directly related to its weight at birth, litter size, place of birth of kit and parity order.

Reproductive performance of rabbit females from three paternal lines with a different potential for growth rate and resilience

A total of 197 nulliparous rabbits (from three paternal lines) were used to test potential strategies to overcome the consequences on reproduction associated with the selection for high growth rate. The R line was selected for growth rate during the growing period for 37 generations, the RF line was founded through a high selection intensity of elite animals of the R line, and the RFLP line, which was obtained by backcrossing RF animals with the LP line (a long-lived productive maternal line, characterised by high resilience). BW, perirenal fat thickness, fertility, daily feed intake, milk yield and blood metabolites of females were controlled from 1st artificial insemination to 3rd parturition. Litter size, litter weight, individual weight and feed ingestion of kits were controlled from birth to weaning. Our results show that RF females were significantly lighter than R and RFLP females throughout the trial (−5.0%; P < 0.05). Furthermore, RF animals had a higher fertility rate than RFLP females, at first cycle (+10.5 percentage points; P < 0.05). However, RFLP had a higher fertility rate than RF females at second cycle (+21.5 percentage points; P < 0.01). On average, RFLP females had higher perirenal fat thickness than R females at parturition (+3.0%; P < 0.05) and higher daily feed intake than of R and RF females during gestation and late lactation (+9.7 and +8.7%, respectively; P < 0.05). RFLP females produced more milk than R and RF females in the two first lactations (+18.5%; P < 0.001). In the first three parturitions, R females delivered fewer kits born alive (−1.7 kits than RF and RFLP; P < 0.05). In addition, R females’ blood had a higher concentration of glutamine and glutamate than RFLP (+24 and +22.7%, respectively; P < 0.05). RFLP litters were heavier than both R and RF litters throughout lactation. However, R kits were heavier at birth than RF and RFLP (+7.9%). Results suggest that the foundation of a paternal line using elite animals could generate females with better early reproductive performance. In addition, backcrossing the RF line with a maternal LP line resulted in a genetic line whose females had a different resource allocation strategy to foster reproduction during the studied period.

Genetic Analyses of Rabbit Survival and Individual Birth Weight.

Simple SummaryKit survival in the first hours after farrowing has been related to the birth weight of kits. In prolific species, newborn survival is controlled both by the genes of the newborns that are involved in vitality, health, and growth (direct genetic effects), and by the dam effects that affect milk yield and other mothering abilities (maternal effects). Genetic parameters of peri and postnatal survival have been estimated traditionally on the performance of dam (assuming normally distributed continuous traits), but it is more appropriate to consider as categorical traits of the kit. The objective of this study was to estimate the heritabilities of kit survival at birth and weaning, as well as the individual birth weight, and the genetic correlations between those survival traits and birth weight using a combined linear threshold model with a Bayesian approach. Heritabilities of survival at birth and weaning, as well as birth weight, were low (0.021 and 0.027) for survival traits and slightly greater (0.146) for birth weight after adjusted litter size. No genetic correlation was found between survival traits. Genetic correlation between survival at birth and birth weight showed a positive value (+0.134 and +0.535 after being adjusted for litter size). These magnitudes of genetic parameter estimates suggested that there is substantial potential for the genetic improvement of kit survival at birth through selection for birth weight.Genetic parameters of kit survival traits and birth weight were estimated on ITELV2006 synthetic line aimed at improving kit survival using a multiple trait linear and threshold model. Data on 1696 kits for survival at birth and at weaning, as well as individual birth weight and litter size were analysed. Genetic effects of kit survival traits and birth weight were estimated based on threshold and Gaussian models, respectively, using a Bayesian approach. The statistical model included, as fixed effects, parity, lactation status, season of farrowing, nest status, cannibalism in kit, place of kit’s birth in the cage and gender, and adjustment for litter size. Posterior means of heritabilities for direct genetic effects of survival at birth and the entire nursing period, as well as birth weight, were 0.018, 0.023, and 0.088, respectively, and were increased when adjusted for litter size to 0.021, 0.027 and 0.146. Genetic correlation between survival traits was zero. Therefore, these traits can be treated genetically as different traits. Genetic correlation between direct effects of survival at birth and birth weight showed positive, but low, value (+0.134) and was increased to +0.535 when the traits were adjusted for litter size. No genetic correlation was found between survival at weaning and birth weight. These magnitudes of genetic parameter estimates suggested that there is substantial potential for the genetic improvement of kit survival at birth through selection for birth weight.

Effects of Dietary Inclusion of Spirulina platensis on the Reproductive Performance of Female Mink.

Simple SummaryProfitability of mink farming depends mainly on the reproductive performance of female animals. Many dietary practices applied previously, to improve health and productivity of mink. Spirulina platensis is a natural dietary supplement, widely used both for human and animal consumption. In previous studies, in many animal species, Spirulina platensis supplementation improved reproductive characteristics. To our knowledge, inclusion of Spirulina in a mink’s diet has not yet been adequately studied. To address this dearth of knowledge, we investigated the effect of dietary inclusion of Spirulina platensis on the reproductive performance of female mink from pre-mating season until kit weaning. A tendency for a higher whelping rate was detected in Spirulina platensis treated animals, while a significant increase in their body weight during pre-mating season was observed. Finally, Spirulina platensis treated animals lost significantly more body weight during late lactation, but without an adverse effect on their or their kit’s survival. Overall, it can be suggested that Spirulina platensis can be used in female mink diets without adverse effects. However, since in the present study only a single dose was used, further studies are required to investigate the effects of higher levels of supplementation.The objective of this study was to investigate the impact of providing Spirulina platensis (Spirulina) on reproductive performance of female mink. A total of 100 adult brown female mink (Mustela vison) were randomly and equally allocated to control group (C group), in which mink were fed basal diet and Spirulina group (Sp group), where mink received basal diet supplemented with 100 mg of Spirulina/kg of body weight. The experiment lasted 5 months, starting from 1 month prior to mating till kit weaning. Weight gain during pre-mating period was higher in Sp group compared to C group (p < 0.001). Sp group remained heavier until the onset of lactation. Subsequently, mink of Sp group lost more weight than C group (p < 0.001) but without an adverse effect on kit survival. A tendency for a higher whelping rate was detected in Sp group (93.61%) compared to C group (81.25%) (p = 0.07). Litter size, as well as weight of kits at weaning, did not differ between groups (p > 0.10). Finally, Sp group weaned numerically more kits compared to C group. Results obtained here showed that Spirulina treated animals tended to an increased whelping rate.

Effects of genotype, gestation length and litter size on the birth weight, litter weight, pre- and post-weaning weight of crossbred kits

BackgroundPerformance of rabbit is hinged on many factors of which the birth weights, gestation length and the litter size are most important. Linear body traits provide vital information on the performance, productivity and carcass characteristics which could be useful tool for the improvement in genetic potentials of rabbits. Therefore, this study investigated the effects of genotype, gestation length and litter size on the birth weight, pre- and post-weaning weight of crossbred kits.ResultsFive breeds: Rex (RX), Dutch-belted (DBT), New Zealand white (NZW), Californian white (CFW) and local breed (LAB) of rabbit were used for the study. A foundation stock of 40 growing rabbits consisting of six does and two bucks were used for the crossing experiment. Genotype exerted significant influence (P < 0.01) on the litter weight at birth as well as on the body weight of the kits at 21st and 35th days. The kit kindled from mating CFWxDBT breeds had the highest mean body weight from birth (91.90 ± 9.84 g) to 35th days (368.25 ± 17.36 g), while the crosses of DBTxCFW recorded the least mean body weight from birth (74.25 ± 1.78 g) to 35th days (332.60 ± 12.54 g). Gestation length significantly (P < 0.05) influenced individual and litter birth weights, pre- and post-weaning weights of kits. Does with short gestation length (29 days) had kits with light body weight compared to those with longer period of gestation (34 days). More so, kits belonging to large litter size (7) had the lowest body weight at birth as well as 21st and 35th day (69.93 ± 1.63 g, 209.57 ± 3.70 g, 319.11 ± 9.22 g) compared to kits that belonged to small litter group size. Highly significant (P < 0.01) and the strongest phenotypic relationships were recorded between body weight at day 21 and day 35 for all crosses, while weak and negative genetic correlation (r = − 0.19) was observed between litter birth weight and individual birth weight of crossbred kits.ConclusionCrossbreeding produces offspring with better performances. Birth weight of kits is a prediction tool for the overall performance of rabbits provided the environment is uninterrupted.

EFFECT OF SUPPLEMENTATION OF PHYTO-ANTIOXIDANT (BAOBAB FRUIT PULP MEAL) ON REPRODUCTIVE PERFORMANCE OF RABBIT DOES DURING HEAT STRESS

A study was conducted to evaluate the influence of a phyto-antioxidant (baobab fruit pulp meal; BFPM) on the reproductive performance of heat-stressed rabbits does. A total of 50 New Zealand White crosses adult rabbit does of 12 months old were used in the present study. The rabbits were randomly allotted into five experimental treatment groups, with ten rabbits per treatment in a completely randomized design. The rabbits were fed diets supplemented with graded levels (0.0%, 2.5%, 3.5%, 4.5% and 5.5%) of BFPM. Parameters monitored were thyroxin and progesterone secretion, serum metabolites, reproductive traits, and physiological performance of the kitten. Initial thyroxin, progesterone, and serum metabolite levels were low in all the treatment groups, and significantly increased during and after pregnancy. BFPM significantly improved litter size and weight of litter and reduced rectal temperature of the kitten. Gestation period, kit weight at weaning, weight gain, and heart rates of kitten did not show any significant difference. It was concluded that reproductive performance of does during heat stress is enhanced by the supplementation of phyto-antioxidants and performance was higher in 5.5% inclusion level of BFPM.

Effects of increasing levels of orange peel extract on kit growth, feed utilization, and some blood metabolites in the doe rabbits under heat stress conditions

One of the most severe consequences of climate change on the rabbit production sector is heat stress. Dietary supplementation of phytochemicals could alleviate the negative impact of heat stress on rabbits. Thirty-six V-line rabbit does with average live body weight (LBW) of 2.672 ± 0.031 kg were randomly allocated into three experimental groups as follows: the control group (OPE0) and the OPE2.5 and OPE5 groups were orally administered orange peel extract (OPE) at doses of 2.5 and 5 mL/doe. The increasing OPE levels significantly improved LBW at partum (p = 0.002) and weaning (p = 0.004), daily and total feed intake from pregnancy until weaning (p = 0.007), daily milk yield per doe at 7th and 14th days (p ≤ 0.05), and milk efficiency (p = 0.001). Litter size at 1st–28th days, litter weight gain, survival rate, and kit weight gain at 21st–28th days of heat-stressed doe rabbits were significantly improved with OPE treatments. The treatment of OPE5 significantly decreased serum glucose, triglycerides, and very-low-density lipoprotein-cholesterol levels of rabbits. The increasing OPE levels decreased significantly total lipid and low-density lipoprotein-cholesterol levels and increased (p = 0.001) high-density lipoprotein-cholesterol concentration in heat-stressed rabbits. In conclusion, the treatment of OPE improved feed utilization, milk efficiency, and reproductive performance and alleviated the drastic impacts of heat stress on rabbits.

Pre-mating plasma prolactin profile affects California doe rabbit reproductive performance

Ovulation failure was associated with a reduction in pre-mating concentrations of oestradiol-17β and prolactin (PRL). The present study aimed to evaluate whether pre-mating PRL levels have a role in the reproductive efficiency of doe rabbits. A total of 78 multiparous California does (2nd parity) were divided, according to plasma pre-mating PRL, into five categories, >20–25, >25–30, >30–35, >35–40, and >40–45 ng/ml. Does in all categories were naturally mated and kindled, then their reproductive measurements and progesterone (P4) levels were determined. Results show that pre-mating PRL averaged 23.60 ± 0.78, 28.00 ± 0.83, 33.46 ± 0.43, 38.17 ± 0.49 and 41.98 ± 0.68 ng/ml in five categories (p < 0.05), respectively, representing the highest distribution (38.5%) in the 3rd-category. Live body weight of doe rabbits, at mating, pregnancy, and parturition increased (p < 0.05) with increasing pre-mating PRL level. The number of services, litter size, and pregnancy rate increased (p < 0.05) by increasing PRL levels. Reproductive traits and P4 level at mid-pregnancy of does, and the average weight of kits at birth increased (p < 0.05) by increasing PRL levels. The pre-mating PRL profile is important for the identification of reproductive performance in doe rabbits.

Reproductive Performance of Hycole Rabbit Does, Growth of Kits and Milk Chemical Composition during Nine Consecutive Lactations under Extensive Rhythm.

Simple SummaryThe reproductive potential and longevity of rabbit does are the real determinants of the economic profitability of rabbit production. Another important characteristic is the quality of rabbit’s milk, as it determines the survival and growth of rabbit kits. The goal of this study was to examine the effect of parity order on the milk quality and the reproductive performance of Hycole does housed under intensive conditions of a commercial rabbit farm. The results of this trial and its duration allowed to trace the reproductive performance of Hycole females throughout their lifespan and to indicate the age boundary of a profitable reproductive performance of Hycole does.The goal of this study was to analyze the reproductive performance of does, growth of their kits, and chemical composition of their milk over nine consecutive parities in order to indicate the boundary of female reproductive profitability. The novelty of this study results from the combinations of three factors: extensive reproductive rhythm, commercial farming conditions, and a period of nine consecutive parities, showing the actual lifespan of a rabbit doe on commercial farms. The data was collected on 60 Hycole females kept at a commercial rabbit farm. Throughout the study, 32 does were excluded due to different reasons (e.g., excluded by means of selection—43.8% and mortalities—25.0%). The does were first inseminated at 28 weeks of age. Following artificial inseminations were conducted 14–15 days after each parturition. All kits were weaned at the age of 35 days. The following characteristics were analysed: body weight of rabbit does at artificial insemination, milk production per lactation, litter size, litter weight, average kit weight, and milk chemical composition. Rabbit does had a significant decrease in kindling rate between the eighth and the ninth parity (by 10.0 percentage points; p = 0.039). The litter size at weaning in the ninth parity was significantly lower to litters weaned at other analysed parities. The amount of milk produced per lactation was affected by the parity order (6.31–6.76 kg; p = 0.042). The litter weights on day 21 and 35 were the lowest at ninth parity. The content of total solids (TS), solids-not-fat, and fat was affected by the parity order on both analysed lactation days. The content of TS and fat in rabbit milk was characterized with a decreasing trend over the analysed period, on both lactation days. The results clearly indicate that rabbit does under extensive reproductive cycles characterize with a very good reproductive performance and can be successfully used for reproduction even up to the eighth parity. However, further research is needed if keeping them longer will not be profitable.

Effect of lighting schedule, intensity, and colour on reproductive performance of rabbit does

&lt;p&gt;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(&lt;em&gt;P&lt;/em&gt;&amp;gt;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 (&lt;em&gt;P&lt;/em&gt;&amp;gt;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 (&lt;em&gt;P&lt;/em&gt;&amp;lt;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.&lt;/p&gt;

Estimation of heritability and repeatability for pre-weaning body weights of domestic rabbits raised in the humid tropics

Heritability and repeatability estimates are needed for the genetic evaluation of livestock populations and consequently for the purpose of upgrading or improvement. Pooled data on 302 progenies from three consecutive parities of purebred rabbit breeds (Chinchilla, Dutch and New Zealand white) raised in Derived Savanna Zone of Nigeria were used to estimate heritability and repeatability for pre-weaning body weights between 1st and 8th week of age. The experiment was carried out at the Rabbitry Unit of the Teaching and Research Farm of the Ebonyi State University, Abakaliki. Traits studied include: Kit Weight at birth (KWB), 2nd week (K2W), 4th week (K4W), 6th week (K6W) and 8th week (K8W). Nested random effects analysis of (Co) variance as described by Statistical Analysis system (SAS) were employed in the estimations. Respective heritability estimates from the sire component (h2S ) and repeatability (R) as intra-class correlations of repeated measurements from the three parities for KWB, K2W, K4W and K8W were 0.59±0.24, 0.55±0.24, 0.93±0.31, 0.28±0.17, 0.64±0.26 and 0.12±0.14, 0.05±0.14, 0.58±0.02, 0.60±0.11, 0.20±0.14. Heritability and repeatability (except R for KWB and K2W) estimates are moderate to high. In conclusion, since pre-weaning body weights in the present study tended to be moderately to highly heritable and repeatable, hence, improvement of rabbits raised in derived savanna zone can be realized through genetic selection criterions.

Effect of punicalagin and human chorionic gonadotropin on body weight and reproductive traits in maiden rabbit does.

Little is known about the effect of punicalagin extracted from pomegranate or in combination with human chorionic gonadotropin on enhancing the productive and reproductive performance in rabbits that gestate for the first time. The impact of punicalagin alone or in combination with human chorionic gonadotropin on maiden doe body weight, progesterone concentrations, conception rate, gestation rate, litter size, and kit weight was investigated in this study. A completely randomized and balanced experimental design was used to allocate 21 naturally mated maiden does at 6 months of age into the following three treatment groups of 7 does each: Control - intramuscular injection with sterilized water only; Treatment 1 - pre-mating intramuscular injection with punicalagin (100 µg/doe) twice a week and once 3 days post-mating; and Treatment 2 - pre-mating intramuscular injection with punicalagin twice a week and human chorionic gonadotropin (25 IU/doe) once 3 days post-mating. Progesterone was assayed from blood samples taken from the ear marginal vein at mating, post-mating, gestation, and post-kindling phases when all does were weighed. Results indicated significantly positive impacts of punicalagin alone or in combination with human chorionic gonadotropin on all doe reproductive traits, birth, and weaning weights of kits. The study clearly demonstrated an improvement in doe fertility, reproductive performance, and kit survival to weaning. In conclusion, PL and PL+HCG improved maternal body weights and their offspring as well as pregnancy outcomes of young rabbits particularly in the 2nd pregnancy, hence findings of this study could be recommended for improving reproductive health and fertility in maiden rabbit does.