Whelping Rate Research Articles

Factors affecting reproductive performance in the Swedish Bernese mountain dog

BackgroundGood reproductive performance is fundamental for the development of a breed. Previous studies have indicated that the Bernese mountain dog has a relatively high prevalence of reproductive problems such as a high prevalence of dystocia and a low mean litter size. When reproduction is impaired, selection for other traits, including improved health, will become more difficult. The aim of this study was therefore to evaluate reproductive data and factors affecting these in the Bernese mountain dog. Data collected by the Swedish Sennenhund Club during the years 2010–2020 were evaluated by statistical analyses.ResultsInformation from 1287 reported matings were included with a total of 614 bitches and 399 sires. For five reported matings that did not result in a litter, there was no information about the male identity. The reported matings resulted in 798 litters (62% whelping rate) from 502 bitches and 314 males. Paternal and maternal age had a significant effect on whelping rate with a negative effect of increasing age (P < 0.01). Median litter size at birth (LSB) was 6.00 (range 0–14) and was significantly affected by both paternal (P = 0.021) and maternal age (P < 0.001). Parity affected litter size at birth with a lower litter size in 4 year old bitches giving birth to their first litter compared to bitches giving birth to their second to fourth litters. Stillbirth occurred in 51.6% of the litters with a total of 15.4% puppies being stillborn. Total puppy mortality, including stillbirth, was 19.1%. The only factor affecting stillbirth was LSB while both LSB and season affected the risk of having post-natal puppy loss in the litter. The total prevalence of caesarean sections (CS) was 33.0%. The risk of CS decreased significantly with increasing parity and increased with increasing age. The risk of CS was significantly higher for litters with 1–2 puppies compared with litters with 3–9 puppies. The coefficient of inbreeding (F) calculated on 5 generations had no effect on any of the outcomes.ConclusionsParity and maternal age had opposite effects on reproductive outcomes with a positive effect of parity on increasing litter size and decreasing CS rate. The proportion of unsuccessful matings was high with a negative effect of increasing age of both males and females.

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.

A retrospective study of the relationship between canine age, semen quality, chilled semen transit time and season and whelping rate and litter size

The objectives of this study were to investigate the effect of the dog’s age, semen quality, and the duration and season of semen transit on whelping rate and litter size after insemination with transported chilled extended semen. The sperm rich fraction was collected from 43 dogs of 18 breeds, which were presented at the Clinic for chilled semen transport, in the period from 2017 to 2021. Immediately after collection, the total sperm concentration and count, motility, membrane integrity (HOS test), the percentage of live spermatozoa and sperm morphology (eosin nigrosin staining) were evaluated. The sperm rich fraction was centrifuged and diluted with Tris – fructose - citrate extender with the addition of 20% (v/v) egg yolk, then chilled and prepared for shipping. A dose consisted of at least 200x106 live, motile, morphologically normal spermatozoa. The data on the dog’s age, chilled sperm transit time, the season of transit, and the whelping rate and litter size after insemination were recorded. The whelping rate was 55.8% with a mean (±SEM) litter size of 4.71±0.58 pups. The total number of spermatozoa was higher in artificial insemination (AI) that resulted in whelping compared to unsuccessful AI (P&lt;0.05). No difference was observed for any of other sperm quality parameters tested, such as the dog’s age or season of transit regarding whelping rate or litter size. Transit time significantly affected the whelping rate (P&lt;0.01), at (mean±SEM) 21.50±1.28 and 37.00±5.59 h in successful and unsuccessful AI, respectively. In conclusion, analysis of the factors related to the dogs identified total sperm count and transit time as factors that significantly affected whelping rates in bitches inseminated with transported chilled extended semen.

Factors influencing parentage ratio in canine dual-sired litters

Breeding a bitch with two different sires during a single estrous cycle has the potential to facilitate rapid genetic gain and improve reproductive performance within a canine breeding colony. There is limited data regarding the factors that contribute to the success of dual-sired litters in domestic dogs, and only anecdotal evidence suggesting that these litters rarely produce offspring from more than one sire. The objective of this prospective clinical study was to investigate multiple factors that likely affect the success of dual-sired litters on whelping rate, litter size and parentage ratio. These factors include: timing of artificial insemination (AI), order of sires, number of AI’s per cycle, semen type, sperm quality and age of sire and bitch. Data collected over a 10 year period from twenty-nine estrous cycles (28 individual bitches of 10 different breeds) were evaluated after an initial AI with frozen semen from the ‘genetically desired’ sire and followed up with a second AI with either fresh (n = 9) or frozen (n = 16) semen or natural mating (n = 4) from a different, ‘back up’, sire. DNA parentage of each pup born was determined by using a primary panel of 288 SNPs. The whelping rate and litter size from previous single sire inseminations per estrous cycle, in the same bitches, (n = 16) over 25 estrous cycles using either fresh (n = 4) or frozen-thawed (n = 21) semen, were analyzed as controls. Of the 29 dual-sired breedings, 26 bitches whelped (89.7%), and 8 litters (30.8%) were of mixed parentage. In the litters of mixed parentage after a dual-sired breeding, a greater proportion of the offspring were from the second sire than the first sire (73.0% and 27.0% respectively; P < 0.05). Interestingly, in litters where all pups were of single sire parentage after a dual-sired breeding, 50.0% of the offspring were by the first sire and 50.0% were by the second sire. For litters of mixed or single paternity produced by dual-sired breeding there was no difference in average litter size. However, on a per estrous cycle basis for each bitch the whelping rate (89.7% v. 76.0%.) and litter size (5.5 ± 2.5 v. 4.0 ± 2.78) of all dual-sired breedings were greater (P < 0.05) compared to previous single-sired breedings (controls) respectively. This study demonstrates that offspring of mixed parentage derived from dual-sired breedings may be achieved. Furthermore, insemination with semen from two different sires may increase the whelping rate and litter size, which is an important consideration when using genetically valuable, or older individuals with potentially reduced fertility.

Factors affecting the reproductive performance of bitches: A prospective cohort study involving 1203 inseminations with fresh and frozen semen

The aim of this prospective cohort study was to utilize multivariable statistical methods to identify factors that significantly affected whelping rate, litter size and gestation length in a large population of bitches of many different breeds, presented for routine breeding management. In addition, we aimed to determine the incidence of dystocia and the proportion of bitches undergoing a caesarean section procedure. A total of 1146 individual bitches representing 84 different breeds contributed 1203 inseminations over the 9 year (2007–2015) study period. Bitches were inseminated with either frozen-thawed (n = 645), fresh (n = 543) or chilled (n = 15) semen from 1371 different males. The mean (SD) whelping rate was 74± 4% and the mean litter size was 5.8 ± 3.1 pups per litter for all bitches in the study. The whelping rate was significantly lower in bitches inseminated with frozen-thawed semen compared with bitches inseminated with fresh semen (71% vs 80% respectively; P < 0.001). Semen that was classified as having poor motility (<30% progressive) resulted in a significantly lower whelping rate (37%) than semen classified as good (30–65% progressive; whelping rate = 67%) or excellent (>65% progressive; whelping rate = 79%). There was a linear decline in whelping rate with advancing age. Greyhounds and Labradors demonstrated a significantly higher whelping rate (88% and 94% respectively) compared with all other breeds (71.3%, P < 0.001). Bitches inseminated with frozen-thawed semen had significantly smaller litter sizes than bitches inseminated with fresh semen (5.4 ± 3.1 vs 6.2 ± 3.0 pups per litter respectively; P = 0.02). Smaller breeds had significantly smaller litters (4.4 ± 2.1 pups) than medium (5.2 ± 2.9 pups), large (5.9 ± 2.9 pups) or giant (6.7 ± 3.8 pups) breeds. For each advancing year of age, litter size decreased by 0.13 pups per litter. The mean (SD) gestation length from LH0 was 65 ± 1.9 d. Greyhounds had a significantly longer pregnancy duration (68.0 ± 1.5 d) than other breeds. For each additional year of bitch age, gestation length increased by 0.11 days (P < 0.01), and for each additional pup per litter, gestation length was reduced by 0.08 days (P < 0.05). Of the 890 bitches for which whelping outcomes were recorded; 409 (46%) whelped normally without assistance, 249 (28%) had an elective C-section, 205 (23%) underwent an emergency C-section and 27 (3%) were medically managed or required veterinary assistance for dystocia. Brachycephalic breeds were 11.3 (95CI = 9.3–17.9; P < 0.001) times more likely to have a C-section compared to all other breeds. Bitches with litter sizes of one or two pups had a C-section rate of 83%, whereas bitches with litter sizes of three or more pups had a C-section rate of 43% (P < 0.001). This study provides important clinical information to optimise whelping rates, litter size and the prediction of whelping in certain breeds for clinicians working in canine reproduction.

Reproductive Parameters of the Dogo Argentino Bitch.

The Dogo Argentino (DA) is the first and only breed from Argentina recognized worldwide. Although its morphologic features have been well established, its normal reproductive parameters are not clearly known. The aim of this study was to determine the main DA bitch reproductive parameters. One hundred and forty-nine surveys were obtained from breeders from Córdoba province, Argentina: one for each intact DA bitch from 1 to 14 years old. The DA bitch reached puberty at an average of 8.93 months. The mean duration of vulval bleeding found in this study was 11.11 days. The clinical signs characteristic for proestrous-estrous were vulval edema (89.93%), bleeding during the time of mating (32.21%), holding the tail to the side (95.30%), and docility during mating (85.91%). DA bitches had a whelping rate of 84%. Out of 299 pregnancies, 89.30% exhibited a normal parturition, 6.69% presented dystocia, 2.68% needed Cesarean section, and 1.34% aborted. In conclusion, the reproductive parameters of the DA bitch are similar to those identified for other large breeds. DA often showed a prolonged vulval bleeding longer than proestrus. Its high whelping rate, its low incidence of dystocia, and its good maternal ability define the DA as a good reproductive breed with normal reproductive functions.

Seasonal and breed effects on reproductive parameters in bitches in the tropics: a retrospective study

To investigate the influence of season and breed on reproductive parameters in bitches raised under tropical climatic conditions. Over a seven year period, from 1998 to 2004, 310 oestrous periods of 53 bitches were observed. The dogs were of various breeds; dobermann (number of bitches/number of oestrous cycles) (n=2/19), German shepherd dog (n=35/211), Labrador retriever (n=14/68) and Rottweiler (n=2/12). In 250 of the 310 oestrous periods, natural matings took place on days 9 and 11 after the onset of pro-oestrus. The whelping rate was analysed for bitches of each breed. Variables, including breed and the whelping rate, by month of the year, were used for analysis of the inter-oestrus interval, gestation length, total number of pups born, number of live pups born and the weight of the pups at birth. A low frequency of oestrous activity was found during the summer. Breeding dogs in the summer resulted in a low whelping rate. No difference (P>0.05) was seen in the whelping rate of each breed: dobermann (70.5 per cent), German shepherd dog (61.5 per cent), Labrador retriever (67.9 per cent) and Rottweiler (100 per cent). The Labrador retriever had a longer inter-oestrus interval (252 [114] and 190 [61] days) (P<0.01) and a larger litter size (8.2 [1.8] and 6.6 [2.8]) (P<0.05) than the German shepherd dog. The environmental factors in summer tend to reduce oestrus incidence and fertility in the bitches. According to litter size, the Labrador retriever seems to have a more efficient reproductive performance than the German shepherd dog. The Labrador retriever had a longer inter-oestrus interval than the German shepherd dog.

Conception problems in the bitch

THE true incidence of infertility in bitches is not known as not all normal bitches that are mated become pregnant. Usually, when fertile dogs are mated to fertile bitches, a...

Artificial insemination with frozen semen in dogs: A retrospective study of 10 years using a non-surgical approach

From 1994 to 2003, a total of 526 bitches of 99 different breeds were artificially inseminated in 685 estrus cycles with domestic ( n = 353) or imported ( n = 332) frozen-thawed semen from 368 males. The overall whelping rate was 73.1% and mean (±S.E.M.) litter size 5.7 ± 0.1 pups. The whelping rate was higher after intrauterine insemination (75.0%; n = 665) than after intravaginal insemination (10.0%, n = 20; P < 0.05). Insemination at the optimal time resulted in a higher whelping rate (78%, n = 559; P < 0.01) and larger litter size (5.8 ± 0.2; P < 0.05) than inseminations performed late or too late (55.7% and 4.5 ± 0.5, n = 61). Two inseminations ( n = 384) yielded a higher whelping rate ( P < 0.05) and mean litter size ( P < 0.01) than one insemination ( n = 241), 78.1% and 6.0 ± 0.2 and 70.5% and 5.1 ± 0.2, respectively. For inseminations performed at the optimal time, however, the whelping rate was not significantly different for bitches inseminated twice (79.3%, n = 358) versus once (76.8%, n = 168), but the litter size was larger (6.0 ± 0.2 and 5.3 ± 0.3). Semen classified as of poor quality (progressive motility <50% or percentage abnormal sperm >20%) resulted in a lower whelping rate ( P < 0.01) than semen classified as of good quality (progressive motility ≥50% and percentage abnormal sperm ≤20%), 61 and 77%, respectively. Small breeds ( n = 50) had a smaller litter size (3.9 ± 0.3; P < 0.01) than larger breeds (medium [5.7 ± 0.3, n = 94], large [5.9 ± 0.2, n = 295] or giant breeds [6.1 ± 0.5, n = 62] [ P < 0.01]). Bitches older than 6 years had a lower whelping rate (68.2%) than younger ones (77.0%; P < 0.05). The duration of pregnancy was longer ( P < 0.01) for bitches with a litter size of <3 pups (61.7 ± 0. 4 days, n = 30) than for bitches with larger litters (60.5 ± 0.1 days, n = 177). These results show the potential of transcervical intrauterine insemination for routine artificial insemination in dogs. The results with frozen semen inseminations were optimised by inseminating bitches ≤6 years old 2 and 3 days after ovulation with semen of good quality from males ≤8 years old.

Comparison of fertility data from vaginal vs intrauterine insemination of frozen-thawed dog semen: A retrospective study

Fertility data from 327 artificial inseminations (AIs) using frozen-thawed dog semen are presented here. The AIs were performed in 274 bitches using semen from 185 males of 76 breeds. The data cover all AIs conducted during 1983 through 1995 at Cryogenetic Laboratories (CLONE) in the United States with AKC-registered and research bitches, and all AIs carried out at the Department of Obstetrics and Gynecology at the Swedish University of Agricultural Sciences in Uppsala, Sweden, using semen frozen by CLONE, in 0.5-mL straws. Semen was frozen using a standardized, three-step liquid nitrogen vapor freezing method. Whelping rates >70% were obtained when post-thaw motility was 40% or higher. The inseminations were made either directly into the uterus using transcervical catheterization with the Norwegian catheter (NIU; 167 AIs) or a fiberoptic endoscope (EIU; 19 AIs), or in the cranial vagina (VAG; 141 AIs). Resulting whelping rates were 84.4% (NIU), 58.9% (VAG; P<0.001), and 57.9% (EIU). Increasing the number of VAG AN per cycle from 1 to 2 enhanced the whelping rate (P<0.05). The mean interval from the first AI to whelping was 61.8 ± 2.4 d, and was longer for VAG AIs (62.7 ± 2.7 d) than for NIU Als (61.2 ± 2.1 d; P<0,001). The mean interval from the last AI was 60.1 ± 1.9 d, and did not differ between VAG AIs (60.2 ± 2.2 d) and NIU AIs (60.0 ± 1.6 d). Gestation length was not influenced by breed or litter size. A total of 1158 pups resulted from the 327 AIs. Litter size was 5.4 ± 3.0 (NIU), 4.0 ± 2.7 (VAG; P<0,001), and 6.0 ± 2.1 (EIU). Litter size was also influenced by breed (P=0.006) and, for VAG AN by the number of inseminations performed per cycle (P=0.009). This study is the largest that has been carried out on frozen-thawed dog semen AI. It shows that using a good method for crYopreservation, together with nonsurgical intrauterine AI employing the Norwegian catheter, can yield whelping rates and litter sizes similar to those reported from well-controlled natural matings. Furthermore, this is the first study to show that intrauterine deposition of frozen-thawed dog semen results in a significantly higher whelping rate and larger litter size than vaginal deposition.

MULTIGENERATIONAL STUDY OF THE EFFECTS OF CONSUMPTION OF PCB-CONTAMINATED CARP FROM SAGINAW BAY, LAKE HURON, ON MINK. 1. EFFECTS ON MINK REPRODUCTION, KIT GROWTH AND SURVIVAL, AND SELECTED BIOLOGICAL PARAMETERS

This study was conducted to determine the multigenerational effects of consumption of PCB-contaminated carp (Cyprinus carpio) from Saginaw Bay ( Lake Huron) on mink (Mustela vison) reproduction and health and to examine selected biomarkers as potential indicators of polyhalogenated hydrocarbon toxicity in mink. The mink were fed diets formulated to provide 0 (control), 0.25, 0.5, or 1.0 ppm polychlorinated biphenyls (PCBs) through substitution of Saginaw Bay carp for ocean fish in the diets. To determine whether the effects of PCB exposure were permanent, half of the parental (P ) animals 1 were switched from their respective treatment diets to the control diet after whelping the first of two F1 generations. Effects of in utero and lactational exposure to PCBs on subse1 quent reproductive performance of the F1 animals were examined by switching half of the first-year F offspring (kits) to the control diet at weaning, while the other half was continued on their parental diet (continuous exposure). Continuous exposure to 0.25 ppm, or more, of PCBs delayed the onset of estrus (as determined by vulvar swelling and time of mating) and lessened the whelping rate. Litters whelped by females continually exposed to 0.5 ppm, or more, of PCBs had greater mortality and lesser body weights than controls. Continuous exposure to 1.0 ppm PCBs had a variable effect on serum T4 and T3 concentrations. Compared to the controls, there were significant differences in kidney, liver, brain, spleen, heart, and thyroid gland weights of the mink continually exposed to 1.0 ppm PCBs. There was an increase in the incidence of periportal and diffuse vacuolar hepatocellular lipidosis in the P1 mink with continuous exposure to increas1 ing concentrations of PCBs. Plasma and liver PCB concentrations of the adult and kit mink were, in general, directly related to the dietary concentration of PCBs and the duration and time of exposure. Short-term parental exposure to PCBs had detrimental effects on survival of subsequent generations of mink conceived months after the parents were placed on ''clean" feed. The lowest observed adverse effect level (LOAEL) for dietary PCBs in this study was 0.25 ppm.

Reproductive efficiency in mink (Mustela vison) treated with the pesticides lindane, carbofuran and pentachlorophenol

Mink are carnivores of agroforestry fringe habitats and are exposed to pesticides that biomagnify within the food chain. Some pesticides are thought to disrupt reproductive and endocrine functions. In Expt 1, four groups of mink (n = 10) were fed either a control diet, or diets treated with lindane (1 mg kg-1 day-1), carbofuran (0.05 mg kg-1 day-1) or pentachlorophenol (1 mg kg-1 day-1) from before breeding until weaning. Mink were mated twice, at 7-8 day intervals. The treatments had no effect on the proportion of mink accepting the first mating; however, lindane and pentachlorophenol caused a decrease in the percentage of females accepting the second mating. Lindane and pentachlorophenol caused a decrease in whelping rate, although litter size was not affected. Carbofuran had no effect on fertility. Mink that mated only once had a lower whelping rate than mink that mated twice; therefore, it could not be determined whether the decreased whelping rates were due to the lack of a second mating or to increased embryo loss. In Expt 2, two groups of mink (n = 15) were fed a control diet or a diet treated with lindane (1 mg kg-1 day-1) from before mating until weaning. Mink were mated twice on two consecutive days. Lindane did not affect mating response at either mating. Whelping rate, but not implantation rate, was decreased by the lindane treatment. The proportion of embryos lost after implantation (implantation scars not represented by kits at whelping) was increased by the lindane treatment. In conclusion, both lindane and pentachlorophenol decreased fertility in mink, and the lindane effect was primarily a result of embryo mortality after implantation.

Semen cryopreservation in dogs and foxes

Abstract Low temperature preservation of canid semen has been a subject of increasing interest among dog breeders, fur breeders and scientists. Research has focused on the use of different buffers, cryoprotectants, egg yolk additions, equilibration and cooling rates, semen packaging techniques, and freezing-thawing protocol. Some laboratories have seen a beneficial effect of post-thaw dilution, especially with vaginal semen deposition. Few reports have given fertility results on a larger scale as a basis for recommended protocol. However, it is established that artificially inseminated frozen semen can yield good fertility results (75–80% whelping rate) in dogs and in blue fox-silver fox crossbreeding, whereas pure breeding with frozen blue fox semen yields fertility results far below those from natural service. More basic research on membrane function during exposure to freezing regimes and media is called for in this species.