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PubMedDate not supplied

The development of a new breed of sheep in Colombia.

A new breed of sheep has been developed in Colombia by crossing Scottish Blackface rams with the indigenous Criolla ewes and then interbreeding the progeny, with selection based on performance. It has been given the name Manchada Paramuna. The breed has been developed to provide the small producer (campesino) with a breeding ewe which has a high level of fertility, a good fleece, and which produces lambs with high survival rate and good growth rate.

Animals↗
PubMed1983

Breeding condition, temperature, and the regulation of salt and water by pituitary hormones in the red-spotted newt, Notophthalmus viridescens.

In vivo integumental transepithelial potential (TEP) in the Eastern red-spotted newt (Notophthalmus viridescens) increases linearly with external [Na+] from 0.1 to 10 mM and is anion independent. Both integumental TEP and osmotic permeability are higher in laboratory-conditioned (LC, terrestrial) than in breeding-condition (BC, aquatic) newts at temperatures of 5-25 degrees. Prolactin (PRL) treatment of LC newts decreased both TEP and rate of water uptake. Arginine vasotocin (AVT) treatment resulted in a substantial increase in water uptake in LC newts, while little or no AVT response was seen in PRL-treated or BC newts. Hypophysectomy (HX) or ergocryptine treatment increased TEP in BC newts, whereas HX + PRL maintained TEP at control levels. Although ergocryptine and HX were without effect on water uptake in BC newts kept at 5 degrees for 9 days, HX + ACTH increased water uptake. HX produced a substantial fall in serum [Na+] in BC newts, while either PRL or ACTH replacement elevated serum [Na+]. Combined ACTH and PRL treatment returned serum [Na+] to control levels. These data suggest that high endogenous prolactin plays a significant role in maintaining serum [Na+] and integumental permeability and transport characteristics in breeding-condition N. viridescens. Although PRL and ACTH are both sodium retaining in the aquatic breeding stage, these two hormones promote opposite effects on the integument; PRL decreases both water uptake and integumental TEP, whereas ACTH (presumably acting through the adrenals) increases water uptake and possibly TEP.

Adrenocorticotropic Hormone↗
PubMed1992

Reproductive endocrinology of macaroni (Eudyptes chrysolophus) and gentoo (Pygoscelis papua) penguins. I. Seasonal changes in plasma levels of gonadal steroids and LH in breeding adults.

Changes in plasma luteinizing hormone (LH), testosterone, oestradiol, and progesterone were measured throughout the breeding and molt cycle in free-living male and female macaroni (Eudyptes chrysolophus) and gentoo (Pygoscelis papua) penguins, at Bird Island, South Georgia (54 degrees S, 38 degrees W). These two species are sympatric but have a markedly different breeding cycle. In macaroni penguins plasma levels of all hormones, except LH in males, were significantly elevated at the time of arrival at the breeding colony. In both species and sexes plasma LH, testosterone (males), and estradiol (females) levels were highest during nest-building and postcopulation, coincident with the period of frequent agonistic interactions in males and egg-formation in females. Elevated testosterone levels occurred in females of both species during the postcopulation period and may be associated behaviourally with both sexes being involved in nest defence. Male birds also had elevated estradiol levels. Following copulation, plasma levels of LH, testosterone, and estradiol decreased to basal levels in both sexes and species and, except for a transient increase in testosterone in male macaroni penguins, remained low through to the end of molt. There was no associated rise in LH or testosterone during premolt and early molt despite a further period of agonistic and social interaction, suggesting that birds were in a photorefractory state at this time. Plasma progesterone showed a pattern of variation different from that of the other hormones. In both species and sexes, plasma levels were elevated between arrival and early chick-rearing and then decreased slowly to low levels during molt.

Animals↗
PubMed1990

Experimental Haemonchus contortus infection in three breeds of sheep.

Nine- to 10-month-old Florida Native, St. Croix and Dorset/Rambouillet sheep were infected with Haemonchus contortus. The primary infection was terminated by anthelmintic treatment 9 weeks later and animals were then reinfected with H. contortus. Dorset/Rambouillet sheep showed higher fecal egg counts and decreased packed cell volumes and plasma protein levels compared with the other two breeds during the primary infection. However, no breed differences were found in total worm burdens in either primary or secondary infection. Differences between breeds were also not detected in lymphocyte responsiveness to parasite antigen, H. contortus specific mucosal antibody levels, numbers of abomasal mast cells and globule leukocytes or abomasal histamine levels.

Animals↗
PubMed1991

Trypanosomiasis in different breeds of cattle from Benin.

Blood of different breeds of cattle, namely Lagune from the Atlantic province, Borgou and Borgou x Zebu from the Borgou province, and Somba and Zebu from the Atacora province of Benin, were examined for trypanosome infection. Thick and thin blood smears for trypanosomes, the card agglutination test (CATT), indirect immunofluorescent antibody test (IFAT) and trypanolytic test for antibodies to trypanosomes were used. Trypanosomes were detected in 19.3% (range 9.8-31.4%) of animals by examination of blood smears; antibodies to trypanosomes were found in 89.8% (range 88.4-100%) of samples by IFAT, 50.6% (range 34-87.5%) by CATT and 3.4% (range 1.1-7.1%) by trypanolytic test. Trypanosoma vivax and Trypanosoma congolense were the main species in Benin with a low number of Trypanosoma brucei. Zebu had lower infection rates than trypanotolerant breeds of Benin. The infection rates of various trypanotolerant breeds were not significantly different.

Agglutination Tests↗
PubMed2006

"Let There be Light!" pigeon eggs are regularly exposed to light during breeding.

Light stimulation before hatching initiates the emergence of avian visual lateralisation. Since several studies show that birds benefit from being lateralised, we can conjecture that their clutch is being exposed to light during breeding. We tested this assumption in pigeons with a semi-natural setup where the animals were systematically recorded using a movement detection system throughout their breeding period. The results show that pigeon pairs perform their relieves in a regular way by abandoning their clutch for a mean of about 55 s at approximately every 43 min. Thus, the developing visual pathways are repetitively stimulated by light for cumulatively over 3h before the breeding period ends. It becomes apparent that both the duration as well as the repetitions of light stimulation play a crucial role in the onset of visual asymmetry.

Animals↗
PubMed2006

Nutritional risks to large-breed dogs: from weaning to the geriatric years.

Distinctive risk factors for disease are identifiable throughout life stages of large- and giant-breed dogs. From weaning to maturity, improper nutrition is linked to developmental skeletal diseases. As large dogs mature, skeletal diseases and obesity can lead to osteoarthritis. These dogs are difficult to manage when orthopedic or osteoarthritic disease affects mobility and quality of life, thereby increasing the risk of early death. Gastric dilatation and volvulus is another disease that is leading cause of death in large- and giant-breed dogs. Management of health, including proper nutrition, exercise, and weight control, provides the best opportunity for successful aging of large- and giant-breed dogs.

Aging↗
PubMed2005

Breeding for QX disease resistance negatively selects one form of the defensive enzyme, phenoloxidase, in Sydney rock oysters.

QX disease in Sydney rock oysters (Saccostrea glomerata) is caused by the paramyxean protozoan, Marteilia sydneyi. Disease outbreaks occur during summer (January to May) and can result in up to 95% mortality. The New South Wales Department of Primary Industries has been selectively breeding S. glomerata for resistance to QX disease since 1996. Previous work suggests that this breeding program has specifically affected the defensive phenoloxidase enzyme system of oysters. The current study more thoroughly characterises the effect of selection on the different forms of phenoloxidase found in oyster populations. Native polyacrylamide gel electrophoresis (native-PAGE) identified five discrete types of phenoloxidase in non-selected (wild type) and fourth generation QX disease resistant (QXR4) oysters. One electrophoretically distinct form of phenoloxidase, POb, is significantly less frequent in resistant oysters when compared to the wild type population. The frequency of POb also decreased in both the wild type and QXR4 populations over the course of a QX disease outbreak. This suggests that possession of POb makes oysters susceptible to QX disease and that breeding for resistance has resulted in negative selection against this form of phenoloxidase.

Animals↗
PubMed2005

Prevalence of feline infectious peritonitis in specific cat breeds.

Although known that purebreed cats are more likely to develop feline infectious peritonitis (FIP), previous studies have not examined the prevalence of disease in individual breeds. All cats diagnosed with FIP at a veterinary teaching hospital over a 16-year period were identified. Breed, sex and reproductive status of affected cats were compared to the general cat population and to mixed breed cats evaluated during the same period. As with previous studies sexually intact cats and purebreed cats were significantly more likely to be diagnosed with FIP; males and young cats also had a higher prevalence of disease. Abyssinians, Bengals, Birmans, Himalayans, Ragdolls and Rexes had a significantly higher risk, whereas Burmese, Exotic Shorthairs, Manxes, Persians, Russian Blues and Siamese cats were not at increased risk for development of FIP. Although additional factors doubtlessly influence the relative prevalence of FIP, this study provides additional guidance when prioritizing differentials in ill purebreed cats.

Animals↗
PubMed2005

Breeding programmes for TSE resistance in British sheep. I. Assessing the impact on prion protein (PrP) genotype frequencies.

From April 2005, member states of the European Union were required to implement a compulsory breeding programme for resistance to transmissible spongiform encephalopathies (TSEs) in sheep as part of measures to eradicate TSEs from national flocks. In this paper, we assessed the impact of four different breeding strategies on prion protein (PrP) genotype frequencies using a mathematical model which describes in detail gene flow in the British sheep flock. These strategies ranged from the minimum requirements laid down in by EU legislation to compulsory implementation of the current National Scrapie Plan for Great Britain (NSP) ram genotyping scheme. All four strategies were predicted to substantially reduce the frequency of the VRQ allele, which is associated with the highest risk of scrapie, although schemes with more stringent requirements produced a larger reduction. However, there were marked differences in the impact of the strategies on the frequency of other PrP alleles. In particular, restrictions beyond those required by EU legislation were necessary to change the frequency of other PrP alleles substantially. Consequently, a breeding programme which aims to reduce the risk to human health by reducing the frequency of the ARQ allele (associated with the highest risk of BSE in sheep) must place restrictions on ARQ-bearing animals. Similarly, a programme which seeks to increase the frequency of the ARR allele (associated with the lowest risk of TSE) must favour ARR-bearing animals.

Alleles↗
PubMed2005

Breeding soundness evaluations of Senepol bulls in the US Virgin Islands.

The breeding soundness evaluation (BSE) was used to evaluate Senepol (Bos taurus) bulls (n = 495) on St. Croix over a 7-year period. Young, unproven bulls (10-26 months of age) and breeding bulls (16 months to 8.5 years) were tested prior to sale or use in breeding. Inbreeding coefficients were determined for a subset of bulls (n = 290). The percentage of bulls passing the BSE increased (P < 0.0001) with age. Bulls that passed had a higher percentage (P < 0.0001) of normal and motile sperm as well as a larger (P < 0.0001) scrotal circumference than bulls that failed. No bulls failed the BSE for physical soundness traits or other health reasons. The incidence of testicular hypoplasia was 2.5 and 3.3% and the incidence of cryptorchidism was 1.4 and 0.9% in 12- and 16-month-old bulls, respectively, with no occurrence in bulls >20 months. The proportion of all bulls that failed the BSE and received an Unsatisfactory rating for scrotal circumference or sperm motility decreased (P < 0.0001) from >90 to <25% with age. The proportion of all bulls that failed the BSE and received an Unsatisfactory rating for sperm morphology decreased (P < 0.0001) from 99 to 83.3% with age. The inbreeding coefficient was higher (P < 0.03) in bulls that failed the BSE than in those that passed (2.24 +/- 0.19% versus 1.40 +/- 0.32%, respectively). There was a tendency for bulls with testicular hypoplasia or cryptorchidism to have a higher (P = 0.09) inbreeding coefficient than bulls with normal testes (2.90 +/- 0.46% versus 2.13 +/- 0.11%, respectively). In conclusion, Senepol bulls raised under tropical conditions had a low probability of passing the BSE at young ages, but the passing rate increased with age. Older Senepol bulls were more likely to fail the BSE due to abnormal sperm morphology than due to inadequate testicular size or sperm motility. To prevent unnecessary culling, a BSE should not be performed on Senepol bulls <16 months old.

Animals↗
PubMed2006

Influence of sire and sire breed (Gyr versus Holstein) on establishment of pregnancy and embryonic loss in lactating Holstein cows during summer heat stress.

Heat stress has negative effects on pregnancy rates of lactating dairy cattle. There are genetic differences in tolerance to heat stress; Bos taurus indicus (B. t. indicus) cattle and embryos are more thermotolerant than Bos taurus taurus (B. t. taurus). In the present study, the effects of sire and sire breed on conception and embryonic/fetal loss rates of lactating Holstein cows during the Brazilian summer were determined. In Experiment 1, cows (n=302) were AI after estrus detection or at a fixed-time with semen from one Gyr (B. t. indicus) or one Holstein sire (B. t. taurus). Pregnancy was diagnosed 80 days after AI. In Experiment 2, cows (n=811) were AI with semen from three Gyr and two Holstein sires. Pregnancy was diagnosed at 30-40 and at 60-80 days after AI. Cows diagnosed pregnant at the first examination but non-pregnant at the second were considered as having lost their embryo or fetus. Data were analyzed by logistic regression. The model considered the effect of sire within breed, sire breed, days postpartum, period of lactation, and AI type (AI after estrus versus fixed-time). There was no effect of the AI type, days postpartum or milk production on conception or embryonic loss rates. The use of Gyr bulls increased pregnancy rate when compared to Holstein bulls [9.1% (60/657) versus 5.0% (23/456), respectively, P=0.008; data from Experiments 1 and 2 combined]. Additionally, in Experiment 2, cows inseminated using semen from sire #4 (Gyr) had lower embryonic loss (10%) when compared with other B. t. indicus (35.3% and 40%) or B. t. taurus sires (18.2% and 38.5%, P=0.03). In conclusion, the use of B. t. indicus sires may result in higher conception rates in lactating Holstein cows during summer heat stress. Moreover, sire can affect embryonic loss and selection of bulls according to this criterion may result in higher parturition rates in lactating Holstein cows.

Abortion, Veterinary↗
PubMed2005

An epidemiological study of gastrointestinal parasites of dogs from Southern Greater Buenos Aires (Argentina): age, gender, breed, mixed infections, and seasonal and spatial patterns.

A total of 2193 fecal samples from owned dogs were collected during the 2003-2004 period in Southern Greater Buenos Aires, and were evaluated for the presence of intestinal parasites by a flotation-centrifugation method. The overall prevalence was 52.4%, and the 11 species found were: Ancylostoma caninum (13%), Isospora ohioensis complex (12%), Toxocara canis (11%), Trichuris vulpis (10%), Sarcocystis sp. (10%), Giardia duodenalis (9%), Isospora canis (3%), Hammondia-Neospora complex (3%), Dipilydium caninum (18 cases), Cryptosporidium sp. (5 cases), and Toxascaris leonina (1 case). There was no significant difference in the overall prevalence between genders (female = 50.4%, male = 54.6%), and breeds (pure = 52.3%, mixed = 53%), but prevalence in puppies (<1 year) was higher than in adult dogs (62.7% versus 40.8%, respectively). Only the prevalence of A. caninum differed between genders, with higher values for males. The prevalences of six of the parasite species showed a decreasing trend with increasing host age, and an inverse pattern was found for two other species. The prevalences of three protozoa were significantly higher in pure-breed dogs, and those of two nematodes were significantly higher in mixed-breed dogs. The prevalences of T. canis, A. caninum, and T. vulpis were spatially heterogeneous with a clear Southwest-Northeast gradient. Only prevalences of Sarcocystis sp. and G. duodenalis showed seasonal variation. The frequency distribution of the number of species per fecal sample did not differ from a random distribution. Results obtained throughout the world were discussed.

Age Factors↗
PubMed2026

Genetic legacy effects in a mungbean-wheat rotation reveal potential to breed for system-level yield gains.

Legume crops provide protein-rich food, serve as critical disease breaks in cereal rotations, and contribute to soil fertility through symbiotic nitrogen fixation. However, crop improvement programs typically focus on within-crop performance rather than system-level benefits. We hypothesize that legacy effects (the influence of one crop's genotype on subsequent crop performance) are under genetic control and could be targeted in breeding programs. To test this, we evaluated how 309 genetically diverse mungbean genotypes influenced subsequent wheat performance. The mungbean panel was grown, followed by a single wheat cultivar sown in the same plots. Remarkably, wheat yield varied by nearly 1 t ha-1 (2.52-3.49 t ha-1), depending solely on the preceding mungbean genotype. Legacy effects showed moderate heritability (H2: 0.43-0.65), suggesting untapped genetic potential for breeding. However, these estimates were derived from a single site and season and require validation across environments. Analyses of mungbean traits, soil properties, and volatile organic compounds identified root architecture, symbiotic nitrogen fixation, and the soil microbiome as potential contributors to legacy effects, although these mechanisms remain to be tested directly. Haplotype mapping identified genomic regions in mungbean associated with wheat yield and, to a lesser extent, grain protein, revealing trade-offs between within-crop performance and legacy effects. Genetic simulations based on empirically derived marker effects compared genomic selection strategies targeting mungbean yield, wheat yield, or both simultaneously. A selection strategy placing equal weight on mungbean yield and subsequent wheat yield (50:50 weighting) achieved simultaneous gains in both crops (19.5% and 7.6%), highlighting the potential to breed for system-level productivity with reduced input requirements.

crop rotations↗
PubMed2006

Plasma steroids and steroid-binding capacity in male semelparous dasyurid marsupials (Phascogale tapoatafa) that survive beyond the breeding season in captivity.

The semelparous dasyurids display a unique life history, in that all males die within a few weeks of the completion of the breeding season. Studies of several semelparous species have revealed that the male die-off is stress-related, and accompanied by increased plasma androgen and cortisol levels and decreased corticosteroid binding capacity, resulting in suppression of immune and inflammatory responses. This study examines the endocrine profile of male brush-tailed phascogales (Phascogale tapoatafa) that survive beyond the breeding season in captivity. Plasma cortisol, corticosteroid binding globulin and albumin levels were monitored in both males and females and steroid partitioning calculated. Captive males surviving beyond the breeding season did not show the elevation in plasma cortisol and decrease in corticosteroid binding capacity reported in wild males. Plasma albumin concentrations also remained constant during the sampling period. These data indicate that captive males do not undergo the same stress response described in wild populations.

Animals↗
PubMedDate not supplied

Feasibility and implications of breeding sheep for resilience to nematode challenge.

There are potentially 2 different types of host response which could be targeted when seeking to breed sheep which require minimal frequency of anthelmintic treatment to maintain acceptable health and productivity in the face of nematode challenge. These are "resistance" (the ability to suppress the establishment and/or subsequent development of a parasite infection), and "resilience" (the ability to maintain relatively undepressed production while subjected to parasite challenge). Most studies have concentrated on resistance, and used faecal worm egg count (FEC) as the selection criterion. However, in Romney sheep in New Zealand, it has become apparent that "resistance to infection" does not equate to "disease resistance" in the strict sense. Although genetically low FEC Romney lambs have been shown to have significantly reduced burdens of the most important nematode species, they nevertheless appear to have no significant production advantages over their higher FEC counterparts when all are grazed together under the same larval challenge. Furthermore there is evidence of an unfavourable association between FEC and dagginess (soiling of the breech area) suggesting that some forms of host response to nematode challenge may result in diarrhoea. Our results suggest that the main benefits of selectively breeding for low FEC are likely to be derived indirectly as a result of reduced pasture contamination. This has led us to investigate resilience as a possible alternative breeding option to resistance. Over a period of 3 years approximately 14,000 progeny of 213 different rams were tested for resilience (assessed in terms of drench requirements using an individual "on demand" treatment procedure), as well as growth rate, dag-score, FEC and fleece-weight. Overall the heritabilities of various measures of resilience examined proved to be relatively low (ranging between 0.10 +/- 0.03 and 0.19 +/- 0.04), although estimates varied between flocks and years possibly as a result of differences in the severity of challenge. Nevertheless, results suggested that progeny-test selection for resilience would lead to lambs with higher growth rates and lower dags-scores when left undrenched on infective pasture. In contrast to some Australian results we found no positive association between resilience to mematode challenge and resistance to infection. If the potential benefits of both resistance and resilience are to be captured our results suggest that an index selection procedure will be needed.

Animals↗
PubMed2001

Effect of short-term treatment with bovine somatotropin at estrus on conception rate and luteal function of repeat-breeding dairy cows.

We studied the effect of recombinant bovine somatotropin (rbST) at the time of estrus on progesterone concentrations and conception rates of repeat-breeding Holstein cows. We used repeat-breeding cows of varied parity (n = 510). All the animals were clinically healthy and had had at least three unsuccessful services before entering the study. After detection of estrus, the cows were randomly assigned to either a treated (n = 201) or a control (n = 309) group. The animals in the treated group were given rbST (500 mg s.c.) at the time of estrus and again 10 d later. Artificial insemination was performed 12 h after the first detection of estrus. In order to evaluate the effect of rbST on luteal function, blood samples were taken from 10 cows in each group every 3 d for 18 d, starting on the day of insemination (Day 0) to determine progesterone concentrations. Conception rates were significantly higher (P < 0.05) in the cows treated with rbST (29.3%) than in the control cows (16.9%). The effects of rbST were maximal in cows with 8 or more previous unsuccessful services and in cows with 2 to 4 calvings. Progesterone concentrations tended to be higher in nonpregnant cows that were treated with rbST than in those that were not treated. The difference between groups was significant (p < 0.05) on Day 18 after insemination. In pregnant cows there were no significant differences in progesterone concentrations between treated and nontreated animals at any time. Treatment with rbST at estrus improved the conception rate of repeat-breeding Holstein cows. This effect was associated with an increase in circulating progesterone concentrations on Day 18.

Animals↗
PubMed1997

Age, breed, sex and seasonality as risk factors for equine laminitis.

A case-control study was conducted at the Texas Veterinary Medical Center between January 1, 1986 and December 31, 1991. Logistic regression was used to assess age, breed, sex, and seasonality as risk factors for equine laminitis. There were 70 acute cases, 183 chronic cases, and 779 controls. No statistical association was found between age, breed, sex, or seasonality and the diagnosis of acute laminitis. For chronic cases, the estimated odds ratio was statistically significant for age (OR = 1.05, 95% CI (1.02, 1.08)) and for the diagnosis of laminitis in the third quarter of the year (OR = 2.57, 95% CI (1.55, 4.25)) relative to the first quarter. There was no statistical association between breed or sex and chronic laminitis.

Age Factors↗