Aflatoxicosis in rabbits: Effectiveness of Egyptian raw bentonite in prevention or diminution the detrimental effects of naturally aflatoxin contaminated diets

Thirty five females and 15 males of New Zealand White mature rabbits about 6 months of age, were assigned to 1–5 dietary treatments (7 does+3 bucks for each): uncontaminated control diet, naturally aflatoxin contaminated diet without or with 1,2 and 3% bentonite. Rabbit fed with the aflatoxin-diet had a decreased (P<0.01 or 0.05) physical semen characteristics of bucks and a reproductive performance traits of does. The values of conception rate (%), gestation length (days), litter size (n) and litter weights (g) at birth and viability (%) of litters of doe rabbits, fed with the aflatoxin-diet, recorded, respectively: 64.5; 31.0; 4.4; 275.0 and 57.1 versus 85.6; 30.3; 7.9; 508.0; and 100 for those fed with the uncontaminated diet. Addition of bentonite to the aflatoxin contaminated diet improved in general the physical semen characteristics of buck and reproductive performance traits of doe rabbits. The results of the study demonstrate that adding 1% of Egyptian raw bentonite to the naturally aflatoxin contaminated rabbit diets can provide an effective, cheap and safe practical technique for preventing the aflatoxicosis in mature rabbits.     

Effect of breeding system, cycle and cage size during fattening on rabbit doe and growing rabbit performance under heat stress

In order to evaluate heat stress and circadian rhythm 46 nulliparous rabbit does with a BW of 3.67 ± 0.05 kg (s.e.) were used. They were clipped once or not and rectal temperature, feed and water intake were recorded for 24 h. From this group, 43 rabbit does were mated 7 days after rectal measurements, and randomly assigned to one out of two breeding systems (including in both systems rabbit does that had been clipped or not). In the control one (C) rabbit does were mated 14 days after parturition and litter weaned at 35 days of age, and in the extensive one (E) they were mated 21 after parturition and weaned at 42 days of age. Rabbit doe and litter performance were recorded for 6 months (first three cycles). Two hundred twenty-eight weaned rabbits were divided into two cage sizes: 0.5 and 0.25 m² with eight and four rabbits per cage, respectively, to study growing performance. Farm and rectal temperatures were minimal and feed and water intake maximal during the night (P < 0.001). Unclipped rabbit does showed higher rectal temperature (P = 0.045) and lower feed intake (P = 0.019) respect to clipped does, which are symptoms of heat stress. Neither breeding system nor cycle number influenced fertility, total number of kits born, born alive or dead per litter (91.6%, 6.98, 5.80 and 1.19 on average, respectively). Kit mortality during lactation tended to increase in E compared with C group (48.5% v. 63.4%; P = 0.070), reducing the number of kits at weaning per litter by 33% (P = 0.038). It also increased in the second and third cycles compared with the first (P ⩽ 0.054). It resulted that feed efficiency (g weaned kits/g feed intake does + litter) tended to decrease in E respect C group (P = 0.093), whereas it was impaired successively from the first to the third cycle by 48% (P = 0.014). Growing rabbits from the E group were heavier at weaning (by 38%; P < 0.001), showed a higher feed intake (+7.4%) and lower feed efficiency (−8.4%) throughout the fattening period (P ⩽ 0.056) respect to C group. However, age at slaughter was not different respect to C group (77.3 days on average). Cage size had minor influence in growing performance. In conclusion, rabbit doe and litter productivity impaired when lactation is extended from 35 to 42 days and along successive reproductive cycles.     

Is caprine arthritis encephalitis virus (CAEV) transmitted vertically to early embryo development stages (morulae or blastocyst) via in vitro infected frozen semen?

The aim of this study was to determine, in vivo, whether in vitro infected cryopreserved caprine sperm is capable of transmitting caprine arthritis-encephalitis virus (CAEV) vertically to early embryo development stages via artificial insemination with in vitro infected semen. Sperm was collected from CAEV-free bucks by electroejaculation. Half of each ejaculate was inoculated with CAEV-pBSCA at a viral concentration of 10⁴ TCID₅₀/mL. The second half of each ejaculate was used as a negative control. The semen was then frozen. On Day 13 of superovulation treatment, 14 CAEV-free does were inseminated directly into the uterus under endoscopic control with thawed infected semen. Six CAEV-free does, used as a negative control, were inseminated intrauterine with thawed CAEV-free sperm, and eight CAEV-free does were mated with naturally infected bucks. Polymerase chain reaction (PCR) was used to detect CAEV proviral-DNA in the embryos at the D7 stage, in the embryo washing media, and in the uterine secretions of recipient does. At Day 7, all the harvested embryos were PCR-negative for CAEV proviral-DNA; however, CAEV proviral-DNA was detected in 8/14 uterine smears, and 9/14 flushing media taken from does inseminated with infected sperm, and in 1/8 uterine swabs taken from the does mated with infected bucks. The results of this study confirm that (i) artificial insemination with infected semen or mating with infected bucks may result in the transmission of CAEV to the does genital tack seven days after insemination, and (ii) irrespective of the medical status of the semen or the recipient doe, it is possible to obtain CAEV-free early embryos usable for embryo transfer.     

Breed and experience effect on the sexual behaviors of Damascus and Egyptian-Nubian goat bucks

This study compares the sexual behaviors of bucks from two pure breeds of goats, Damascus and Egyptian-Nubian (Zaraibi), and assesses their relationships with the pregnancy and kidding rates of their inseminated does. Twenty-three bucks (12 Damascus and 11 Egyptian-Nubian bucks) were used in this study. These bucks were either in their first season of service (N =12, with an average age of 1.51 years) or had been previously used in service for several seasons (N = 11, with an average age of 3.34 years). Buck service behaviors toward estrous does were continuously recorded for 30 minutes from the moment of appearance of the doe. Egyptian-Nubian bucks were highly sexually active with estrous does in comparison with Damascus bucks. They required less time to mount and ejaculate for the first (P < 0.04) and second times (P < 0.0002) and tended to sniff, nudge and vocalize more frequently than Damascus bucks. In addition, Egyptian-Nubian bucks had more ejaculations and a higher mating efficiency (27.48% vs. 10.21%, P < 0.001), and their inseminated does had a higher pregnancy rate and larger litter sizes. Regarding the effect of experience, the data revealed a limited influence. No significant differences in sexual behavior were recorded between younger and older bucks. Conversely, pregnancy, kidding rates, and litter size were not influenced by the total number of ejaculations. From these results, it can be concluded that there were sexual behavior differences as a function of breed between Damascus and Egyptian-Nubian bucks and that experience had little impact in this study.     

The effect of seminal sperm concentration on sperm transport in the reproductive tract of female rabbits treated with progesterone or diethylstilbestrol

Forty-two mature Baladi female rabbits were used in a randomized 3x2 factorial experiment to determine the effects of three treatments (control, progesterone injection: 2 mg/doe and DES injection: 0.1 mg/doe) and two semen sperm cell concentrations (1x10(6) and 60x10(6) sperm/0.25 ml semen on sperm transport and distribution in the female reproductive tract. The injections were given for three consecutive days after which rabbits were injected with 5 IU HCG and inseminated with 0.25 ml semen. The does were sacrificed 10 hrs after insemination and the sperm were recovered and counted from the oviducts, uterine horns, cervices and vagina. Total spermatozoa recovered was high when rabbits were inseminated with 60x10(6) sperm as compared to those inseminated with 1x10(6) sperm. When rabbits were injected with progesterone or DES, the number of sperm recovered relative to the total number of sperm inseminated was high in rabbits inseminated with 1x10(6) sperm, in comparison to those inseminated with 6x10(6) sperm. The number of sperm recovered was highest from cervix which was followed by vagina, uterus and oviducts. DES increased the number of the total sperm recovered while progesterone decreased the number as compared to control. This trend was also observed within the different segments of the reproductive tract and with groups inseminated with 1x10(6) or 60x10(6) sperm/0.25 ml semen. The effect of DES was more obvious with does inseminated with low sperm numbers. Significant correlation coefficients were found between the sperm numbers recovered in the uterus and oviducts and in the cervix and uterus of all groups of rabbits.     

Reproductive performance of high growth rate gilts inseminated at an early age

The aim of this work was to determine if gilts, which have a high growth rate (GR) could be mated earlier without reducing the reproductive performance or increasing the culling rate up to the third parity. Gilts of Camborough 22 (C22, n=568) breeding were mated and allocated into three groups according to weight and age on the insemination day. G1 (n=164)-gilts with a GR>or=700 g/d and inseminated at <210 d. G2 (n=165)-gilts with a GR>or=700 g/d and inseminated at >or=210 d. G3 (n=239)-gilts with a GR<700 g/d and inseminated at >or=210 d. All females were fed ad libitum from 150 d on and were inseminated at their second estrus or later. The minimum weight at mating was 127 kg. Three parities were studied, with farrowing rate, litter size and culling rate being compared. At the first parity, G2 gilts produced, on average, one more piglet than the other groups (P<0.05). However, when analyzing three parities, there were no differences in total born (11.6 x 12.3 x 11.7), farrowing rate (87.1% x 88.7% x 89.8%) and culling rate (30.2% x 25.3% x 28.2%) among G1-G3 groups, respectively (P>0.05). In conclusion, gilts, which had a minimum weight of 127 kg can be inseminated at their second or greater estrus, between 185 and <210 d of age, without impairing their productive performance over three parities.     

Influence of supplemental dietary sprouted wheat on reproduction in artificially inseminated doe rabbits

The sprouted wheat contains great amounts of 6-methoxybenzoxazolinone (6-MBOA) a phenol compound that stimulates reproduction in certain small wild herbivorous mammals. The objective of the present study was to evaluate the effect of dietary sprouted wheat as supplement on reproduction in artificially inseminated doe rabbits. Two-month-old New Zealand White doe rabbits (n = 48) were randomly allocated to one of two treatments: (1) pelleted diet plus sprouted wheat for 6 consecutive days prior to service, (2) pelleted diet only (control). First insemination occurred when does reach 3200g body weight and bred 6 days after parturition across 6 months period during summer and autumn. Records from 41 does completing the experiment accounted for 192 inseminations and 142 kindlings equivalent to 4.6 +/- 0.15 and 3.5 +/- 0.15 litters per doe, respectively. Mean daily intake of sprouted wheat on wet and dry matter bases were 196.1 +/- 7.5 and 75.4 +/- 2.9g, respectively. The number of young born produced per doe during the trail was significantly (P = 0.02) greater in does fed sprouted wheat (28.1 +/- 1.2 versus 23.6 +/ -1.3 control). Does fed sprouted wheat had 0.65 +/- 0.06 receptivity rate at AI over 28 per cent greater (P = 0.001) than does in the control treatment. Sexual receptivity was not influenced by physiological status of does and season (P > 0.05). Diet and season had no effect (P>0.05) on kindling rate. However, physiological status had an effect (P = 0.002) on this variable. Kindling rates for nulliparous, lactating and non-lactating does were 0.95 +/- 0.08, 0.63 +/- 0.04 and 0.78 +/ -0.11, respectively. Sexually receptive does had a greater (P = 0.0001) kindling rate (0.95 +/- 0.05) than non-receptive females (0.63 +/-0.05). Does fed sprouted wheat produced larger (P = 0.02) litters than those in the control group: 7.7 +/- 0.30 and 6.8 +/- 0.32, respectively. There was an effect of season (P = 0.04) on the size of the litter at birth. Largest litters were born during autumn (7.9 +/- 0.37) than during summer (6.6 +/- 0.41). Receptive does had more (P = 0.002) young in the litter (7.9 +/- 0.28) than non-receptive (6.6 +/- 0.35). Feeding sprouted wheat as a source of biological 6-MBOA enhanced sexual receptivity and prolificacy in artificially inseminated doe rabbits bred in summer and autumn.     

Controlled doe exposure as biostimulation of buck rabbits

Female exposure of males could be a low-cost biostimulation option that benefits AI in commercial rabbit operations by improving buck rabbits reproductive performance. The objective of the study was to evaluate exposure of buck rabbits to females as a biostimulation option to improve reproductive potential. Treatments were: exposure (biostimulated) or not (control) of bucks to does. Bucks were New Zealand White, 15-month-old, sexually experienced and fertile. Experimental design was completely random with nine replications, experimental unit was one buck. Doe exposure was permanent using replacement pubertal does housed in an adjacent wire-mesh cage and changed for new ones every other week. Semen collection lasted 14 weeks (late winter and early spring) twice a week with two ejaculates at each collection. Analyses of variance were under a mixed model: treatments, ejaculate number and season were fixed and rabbit random effects and buck weight at each collection as covariable. Biostimulated bucks showed greater (P<0.05) reproductive potential due to: 7% lesser reaction time (greater libido); and increased semen volume (40%), sperm motility (29%), sperm per ejaculate (31%), normal alive motile sperm (65%) and number of semen doses (64%). Semen characteristics differed by season in control bucks but not in doe exposed bucks (treatment × ejaculate number, P<0.05). Reproductive potential in spring was greater (P<0.05) than in winter in both treatments. Doe exposure is a biostimulation method that improves sexual drive and sperm production and quality of buck 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.     

Developmental toxicity of soman in rats and rabbits

Soman (GD; phosphonofluoridic acid, methyl-,1,2,2-trimethylpropyl ester) is an organophosphate compound with potent anticholinesterase activity. To determine developmental toxicity, soman was administered orally to CD rats on days 6 through 15 of gestation at dose levels of 0, 37.5, 75, 150, or 165 micrograms/kg/day and to New Zealand White (NZW) rabbits on days 6 through 19 of gestation at dose levels of 0, 2.5, 5, 10, or 15 micrograms/kg/day. At sacrifice, gravid uteri were weighed and examined for number and status of implants. Individual fetal body weights and external, visceral, and skeletal malformations were recorded. Mean maternal weight changes, fetal implantation status/litter, fetal weight, and fetal malformations/litter were compared between dose groups. Monitors for maternal toxicity were net body weight change, treatment weight change, mortality, and clinical signs of toxicity such as lethargy, ataxia, and tremors. Maternal rats and rabbits in the high-dose groups exhibited statistically significant increases in toxicity and mortality when compared to controls. There were no significant dose-related effects among dose groups in the prevalence of postimplantation loss, malformations, or in average body weight of live fetuses per litter. There was no evidence of increased prenatal mortality or fetal toxicity in the CD rat or NZW rabbit following exposure to soman, even at a dose that produced significant maternal toxicity.     

Effect of number of motile sperms inseminated on reproductive performance of rabbit does

The relationship between the number of motile sperms inseminated and fertility rate and litter size at birth in rabbits was investigated. A total of 651 artificial inseminations on multiparous rabbit does in different physiological states (lactating or not; sexually receptive or not) were inseminated with a number of motile cells/dose varying from about 1-20 x 10(6). The statistical model computed the following traits: maximum expected value (a), rate of approach to this value (b) and number of motile spermatozoa/dose needed to obtain threshold level (95% of the maximum). The physiological condition of the doe affected the reproductive performance. The sexual receptivity had significant effect during lactation: non-receptive does had the lowest fertility (a: 43.70%; P < 0.05) while no significant differences were found in non-lactating ones (73.80 vs. 89.11%). Also the rate of approach to this maximum was different: non-receptive does showed a higher dependence on spermatozoa number than receptive females (b: 0.69 and 0.58, respectively, in lactating and non-lactating does) and consequently more spermatozoa (13.1 and 11.1 x 10(6) motile/dose) were needed to reach the threshold value. The physiological state of the does did not affect litter size and only 4.1 x 10(6) of motile spermatozoa/dose are needed to reach the threshold value.     

Differences in productive robustness in rabbits selected for reproductive longevity or litter size

The aim of this work was to evaluate the ability of a line selected for reproductive longevity (LP) to confront productive challenges compared to a line selected during 31 generations for litter size at weaning (V). A total of 133 reproductive rabbit does were used (72 and 61 from LP and V lines, respectively). Within each line, three groups with different levels of productive effort were planned: PP9, inseminated at day 4 after the first partum and with nine kits during the second partum, and inseminated after first weaning (30 days) and with nine (PW9) or five kits (PW5) during the second partum. The reproductive performance, body condition (perirrenal fat thickness (PFT)) and lipolytic response were controlled. LP does showed greater mean live weight (LW; +128 g; P < 0.05), PFT (+0.47 mm; P < 0.05) and estimated body energy (EBE; +0.29 MJ/kg; P < 0.01) than V does at second partum. However, LP does that mated at first post partum did not significantly differ in EBE relative to V does at second partum. During the first week of lactation, dry matter (DM) intake was similar for both lines (94 and 95 g DM/kg LW0.75 day for V and LP does, respectively). There was a significant difference in milk yield between both lines during the first week when litter size was nine (60 v. 54 g of milk/kg LW0.75 day for LP and V does, respectively; P < 0.01), but no difference when litter size was five. Consequently, when litter size was nine, LP does showed a lower recovery of PFT (0.6 mm less; P < 0.05) than V does during the first 10 days of lactation. However, when litter size was five, LP does showed a higher LW (+210 g; P < 0.05) than V does at 10 days of lactation and a similar recovery of PFT. During the last 3 weeks of the lactation, LP does showed a higher feed intake (+6 g DM/kg LW0.75 day; P < 0.05) and milk yield (+27 g/day; P < 0.001) than V does when litter size was nine, resulting in no significant differences in LW at 30 days of lactation. However, when litter size was five, both lines showed similar feed intake and milk yield, maintaining their differences in LW at 30 days of lactation (+206 g for LP does; P < 0.05). These results show that the rabbit line selected for reproductive longevity is more robust with respect to coping with productive challenges, than a line selected for reproductive intensity.     

Aminopeptidase activity in seminal plasma and effect of dilution rate on rabbit reproductive performance after insemination with an extender supplemented with buserelin acetate

Ovulation induction in artificially inseminated rabbits by adding GnRH synthetic analogues in the seminal doses is a welfare-orientated method to induce ovulation in rabbits and could have some advantages in field practice. This study was conducted to determine the effect of male genotype on the aminopeptidase activity in rabbit seminal plasma and the effects of dilution rate of semen on availability and reproductive performance when buserelin acetate is added to the seminal dose. To study the aminopeptidase activity, 12 mature bucks belonging to a paternal line and 12 from a maternal line were used. The bucks from the paternal line were used to study the effect of dilution rate on the availability of buserelin acetate after 2 hours of dilution and on the reproductive performance of the doses after artificial insemination of 389 commercial crossbreed does. Aminopeptidase activity in seminal plasma is dependent on the male genotype. The paternal line resulted 27% more aminopeptidase activity than the maternal line (P < 0.05). On the other hand, semen diluted 1:20 exhibited a marked increase in the availability of buserelin acetate and the fertility in this group was significantly higher than females from dilution rate 1:5 group, which showed similar results to that of the negative control group (does inseminated with semen diluted 1:20 in non–GnRH-supplemented extender). We conclude that the bioavailability of buserelin acetate when added to the seminal dose appears to be determined by the activity of the existing aminopeptidases and is consequently affected by the dilution rate used to prepare the artificial insemination doses.     

The reproductive response to the male effect of 7- or 10-month-old female goats is improved when photostimulated males are used

The exposure of adult, female, Mediterranean goats during anoestrus to males with induced sexual activity via photostimulation, induces a very high percentage of ovulations. The present work examines the ability of photostimulated bucks to improve the male effect-induced reproductive response of young does over that induced by non-stimulated bucks. A 2×2 factorial experiment was designed, consisting of doe age and buck photoperiod treatments. During seasonal anoestrus, 41 does aged 7 (n=19) or 10 (n=22) months were subjected to the male effect on 10 April; half of each group was exposed to males rendered sexually active by prior exposure to 3 months of long days (16 h of light/day) from 31 October (PHOTO bucks), and half to males maintained under the natural photoperiod (CONTROL bucks). Oestrous activity was recorded daily by direct visual observation of the marks left by male-worn marking harnesses over the 32 days following the bringing of the sexes together (introduction). Doe body weight and body condition were determined weekly. Ovulation was detected by measuring plasma progesterone concentrations twice per week over the 3 weeks after introduction. The ovulation rate was assessed by transrectal ultrasonography. Fecundity, fertility, prolificacy and productivity were also determined. The interaction doe age × buck photoperiod treatment had no effect on any outcome. The percentage of females showing ovulation or oestrus was higher in the does exposed to PHOTO bucks (85% v. 43% for those exposed to CONTROL bucks) they also showed higher fertility (75% v. 43%) and productivity (1.05±0.17 v. 0.57±0.16 kids born per doe serviced) (all P values at least P<0.05). The 10-month-old group showed higher percentage of females showing ovulation, oestrus, fertility and productivity than the 7-month-old does after the male effect (females showing ovulation: 82% v. 42%; showing oestrus: 73% v. 42%; fertility: 73% v. 42% and productivity: 1.09±0.17 v. 0.47±0.14 goat kids born per doe serviced; respectively, all P values at least P<0.05). The present results show that the use of photostimulated males improves the reproductive performance of 7- and 10-month-old does, and may contribute towards increasing their productivity and lifetime reproductive performance.     

Reproductive performance of multiparous rabbit lactating does: effect of lighting programs and PMSG use

This study aims to determine if Pregnant Mare Serum Gonadotrophin (PMSG), used for oestrous synchronization in multiparous lactating does, could be replaced by one of the following lighting schedules without impairing reproductive performance: (a) 12-h L (light)/12-h D (dark) or (b) 8-h L/16-h D, until day 6 before artificial insemination (AI), when in both cases photoperiod was changed to 16-h L/8-h D and maintained until the day of AI, and in the following 4 days post Al the light hours were progressively reduced to the initial schedules. Two groups of 20 does each were respectively submitted to one of the lighting schedules specified above. All does were artificially inseminated in 6 consecutive cycles at 42 days intervals. In the first, third and fifth AIs, PMSG (20 IU/doe via sc 48 h before AI) was used in the two groups of does, whereas in the second, fourth and sixth Als no hormonal treatment was used. Degree of oestrous synchronization (also referred in text as sexual receptivity) was estimated by the colour of the vulva at AI. Reproductive performance of does was evaluated based on fertility (kindling rates), prolificity, mortality at birth, mortality at 21 days post birth, weight of the litter at 21 days post birth and number of weaned rabbits. Oestrous was better synchronized when PMSG was used with any of the two lighting programs. Without using PMSG, a photoperiod of 12-h L/12-h D until 6 days before AI resulted in a better sexual receptivity of does than 8-h L/16-h D. Fertility, prolificity, mortality of young rabbits at 21 days, the weight of the litters at 21 days and the number of weaned rabbits did not vary with the lighting program and were not affected by the PMSG treatment. Mortality at birth, however, was higher (+1 dead kit per litter) in litters housed under a light program of 12-h L/12-h D. Global productivity (number of weaned rabbits per 100 inseminated does) was better when using PMSG, for both lighting schedules. When using a photoperiod of 12-h L/12-h D until 6 days before AI, and omitting the PMSG treatment, global productivity was scarcely reduced, however, it was considerably impaired when using a photoperiod of 8-h L/16-h D until 6 days before AI and no PMSG treatment.     

Control of Psoroptes cuniculi in captive white-tailed deer with ivermectin-treated corn

Psoroptes cuniculi, the ear mite of domestic rabbits, was collected from captive white-tailed deer (Odocoileus virginianus). This is the first report of rabbit ear mite infestations in white-tailed deer in Oklahoma or Texas (USA). In addition to moderate infestations in their ears, two 4-yr-old bucks, two 3-yr-old does, and seven 4-yr-old does showed patchy areas of alopecia along the sides and brisket. Both bucks also had patchy areas of alopecia around the base of antlers. Ear mites were eradicated from all deer except from one doe by providing ivermectin-treated corn to the deer at a rate of 1,000 g (equivalent to 200 mcg/kg of ivermectin)/day/deer for several days. The ear mite infestation in the one doe was eradicated by intramuscularly injection with ivermectin at 400 mcg/kg. After treatment with the ivermectin and eradication of the mites, the alopecia improved and eventually was eliminated. The ivermectin-treated corn also controlled all internal nematode parasites in the deer.     

Developmental toxicity evaluation of sodium thioglycolate administered topically to Sprague-Dawley (CD) rats and New Zealand White rabbits

BACKGROUND: Sodium thioglycolate, which has widespread occupational and consumer exposure to women from cosmetics and hair‐care products, was evaluated for developmental toxicity by topical exposure during the embryonic and fetal periods of pregnancy METHODS: Timed‐mated Sprague–Dawley rats (25/group) and New Zealand White (NZW) rabbits (24/group) were exposed to sodium thioglycolate in vehicle (95% ethanol:distilled water, 1:1) by unoccluded topical application on gestational days (GD) 6–19 (rats) or 6–29 (rabbits) for 6 hr/day, at 0, 50, 100, or 200 mg/kg body weight/day (rats) and 0, 10, 15, 25, or 65 mg/kg/day (rabbits). At termination (GD 20 rats; GD 30 rabbits), fetuses were examined for external, visceral, and skeletal malformations and variations. RESULTS: In rats, maternal topical exposure to sodium thioglycolate, at 200 mg/kg/day (the highest dose tested) on GD 6–19, resulted in maternal toxicity, including reduced body weights and weight gain, increased relative water consumption and one death. Treatment‐related increases in feed consumption and changes at the application site occurred at all doses, in the absence of increased body weights or body weight change. Fetal body weights/litter were decreased at 200 mg/kg/day, with no other embryo/fetal toxicity and no treatment‐related teratogenicity in any group. In rabbits, maternal topical exposure to sodium thioglycolate on GD 6–29 resulted in maternal dose‐related toxicity at the dosing site in all groups; no maternal systemic toxicity, embryo/fetal toxicity, or treatment‐related teratogenicity were observed in any group. CONCLUSIONS: A no observed adverse effect level (NOAEL) was not identified for maternal toxicity in either species with the dosages tested. The developmental toxicity NOAEL was 100 mg/kg/day (rats) and ≥65 mg/kg/day (rabbits; the highest dose tested). The clinical relevance of theses study results is uncertain because no data were available for levels, frequency, or duration of exposures in female workers or end users. Birth Defects Research Part B 68:144–161, 2003. © 2003 Wiley‐Liss, Inc.     

Effects of thalidomide on reproductive function and early embryonic development in male and female New Zealand white rabbits

BACKGROUND : The present work was performed to determine the effect of thalidomide exposure on reproductive function and early embryonic development. METHODS : Twenty‐five female New Zealand White rabbits were orally gavaged with 0, 10, 50, or 100 mg/kg/day thalidomide 14 days prior to mating through to gestation day 7 for a total of 22 days. Treated females were Caesarean‐sectioned approximately 29 days after the date of attempted mating. Following mating with treated females, male rabbits (25/dose) were gavaged with 0, 30, 150, or 500 mg/kg/day beginning 14 days prior to mating with a group of untreated females (25/dose). Doses were administered through mating until the day before sacrifice for a minimum of 56 days. Untreated females were Caesarean‐sectioned 29 days after the last attempted mating. Comprehensive necropsy and histopathology of the reproductive system were performed. RESULTS : Treated females had reduction in body weight gain during gestation. Mating and pregnancy parameters were unaffected by thalidomide. At 100 m/kg, litter averages for corpora lutea, implantations, litter sizes, does with viable fetuses and live fetuses decreased and the number of early resorptions, does with any resorptions, does with all conceptuses resorbed, and the percent resorbed conceptuses per litter increased. The number of early resorptions, the average number of early resorptions per litter, and the percent resorbed conceptuses per litter increased at 10 and 50 mg/kg. There were no thalidomide‐related external fetal malformations. Mating and fertility in male rabbits were unaffected by thalidomide. There was an increased incidence of flaccid testes at 150 and 500 mg/kg and of bilateral small testes in all treated groups. At 500 mg/kg, there was degeneration of the germinal epithelium of the testicles with an increase in multinucleated giant cells in seminiferous tubule and a loss of round and elongating spermatids. CONCLUSIONS : Thalidomide had no adverse effects on mating and fertility in male and female rabbits dosed up to 500 and 100 mg/kg/day, respectively, for 14 days prior to mating. After 56 day of dosing, histopathologic changes with no associated sperm abnormalities were observed in the testicles. Embryonic development NOAEL for treated females mated to untreated males was <10 mg/kg. Corresponding fertility NOAEL for treated males mated to untreated females was 500 mg/kg. Birth Defects Res B 71:1–16, 2004. © 2004 Wiley‐Liss, Inc.     

Effect of zinc on the lipid peroxidation and the antioxidant defense systems of the alloxan-induced diabetic rabbits

The effects of oral zinc supplementation on lipid peroxidation and the antioxidant defense system of alloxan (80-90 mg/kg)-induced diabetic rabbits were examined. Forty-five New Zealand male rabbits, 1 year old, weighing approximately 2.5 kg, were allocated randomly and equally as control, diabetic, and zinc-supplemented diabetic groups. After diabetes was induced, zinc-supplemented diabetic rabbits had 150 mg/L of zinc as zinc sulfate (ZnSO(4)) in their drinking tap water for 3 months. The feed and water consumption was higher in diabetic groups than (P<0.01) healthy rabbits. The body weight was lower in diabetic rabbits compared to control. The blood glucose levels were higher in diabetic groups than controls. The elevated plasma malondialdehyde (MDA) levels were determined in the diabetic group (P<0.01). The glutathione peroxidase (GSH-Px), catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), and ceruloplasmin levels in the diabetic group were decreased by the effect of diabetes but there was no difference between zinc-supplemented diabetic and control rabbits. Serum zinc concentrations were lower in diabetic rabbits but iron (Fe) and copper (Cu) levels in sera were not different among the groups. As a result, it was concluded that daily zinc supplementation could reduce the harmful effects of oxidative stress in diabetics.     

Fertility of fresh and frozen rabbit semen inseminated at different times is indicative of male differences in capacitation time

Some reports indicate that sperm from different males differ in capacitation time, and other reports suggest that freezing sperm may affect their capacitation time. These two variables were specifically studied in rabbits in a fertility trial with 96 does inseminated with approximately 1.6 million motile fresh or frozen sperm from three different bucks at 15, 10, 5, and 0 h before expected ovulation. Fresh semen averaged 84% live (unstained) sperm and 88% had normal acrosomes; corresponding values for frozen sperm were 44% and 54%. On the basis of does that became pregnant, average litter size with fresh semen was 5.5 and with frozen semen was 4.8 (p greater than 0.05), but overall, does bred with frozen semen produced fewer young (p less than 0.05). On the basis of total does and total semen, average litter size from insemination at 15, 10, 5, and 0 h was 2.8, 4.2, 3.8, and 1.7, and average litter size for the three bucks was 4.0, 1.8, and 3.6. There was no interaction of type of semen (fresh or frozen) with the other variables in the model (p greater than 0.05). Bucks and time of insemination affected both the proportion of does that were pregnant and litter size (p less than 0.01). A major interaction between buck and time of insemination (p less than 0.01) was due apparently to both differential sperm survival and probable capacitation time among bucks. This major interaction should be considered in designing in vitro and in vivo fertility studies, and for selecting males for use in artificial insemination.