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PubMed2002

Progesterone profiles of fat-tailed tuj ewes following tactile and visual separation of rams at the beginning of the breeding season.

The aim of this study was to determine the level and duration of progesterone secretion during the sequential oestrous cycles in fat-tailed Tuj ewes following tactile and visual separation of rams during the breeding season. For these purposes, rams were separated from the main flock for 50 days starting from the beginning of the breeding season and 21 ewes were randomly selected for the current experiment. In order to assess luteal activity and the length of oestrous cycles, the ewes were blood-sampled thrice or twice weekly for the measurement of progesterone in plasma. The data showed that 3 +/- 0.2 oestrous cycles were observed in this time window, and the first oestrous cycle observed was shorter (P < 0.05) than the following cycles (mean +/- SEM, 14.6 +/- 0.82, 16.5 +/- 0.48 and 17.0 +/- 0.54 days, respectively, for cycles 1, 2 and 3). Progesterone production was significantly lower in the first oestrous cycle compared with the second and third cycles on days 9, 12 and 14 of the cycles. The follicular periods of ewes showed four accumulations (maximum values using a 3-day moving average technique) throughout the study and the percentages of ewes at each accumulation (peak day +/- 1 day) were 50, 35, 65 and 80% for the first, second, third and fourth accumulations, respectively (P < 0.05). It was concluded that progesterone production was lower and the oestrous cycles were shorter during the first oestrous cycle and that tactile and visual separation of rams at the beginning of the breeding season might enhance the synchronizing effect towards the end of the breeding season in the fat-tailed Tuj ewes.

Animals↗
PubMed2005

Fertility and hatchability in RIR and WL breeds as functionally modified by crossing them in alternate sex combinations (Gallus domesticus).

(1) Four breeding groups of Rhode Island Red and White Leghorn domestic fowl (RIR (female) x RIR (male), RIR (female) x WL (male), WL (female) x RIR (male) and WL (female) x WL (male)) were compared for fertility, hatchability, and their post-insemination sustainability, egg weight loss during incubation and uncovered yolk in abdominal cavity of dead in shell in order to understand the problems associated with the RIR breed in these respects. (2) Crossing RIR (female) with WL (male) or in reverse sex combinations did not improve fertility in comparison to pure RIR chickens and all these groups were less fertile than the pure WL. (3) Unlike fertility, hatchability in RIR improved with the change to either sex partner of the WL breed but the WL (female) x RIR (male) combination was similar to the pure WL (97.72 and 97.12%, respectively). In contrast, crossing RIR (female) with WL (male) resulted in an improvement (86.67%) as compared to pure RIR (76.67%) but still lower than the pure WL and WL (female) x RIR (male) cross. (4) Egg weight loss during incubation was more (20.16%) in pure RIR as compared to RIR (female) x WL (male) (17.13%), followed by WL (female) x RIR (male) (10.28%) and pure WL (9.57%). (5) There were more dead-in-shell embryos with yolks outside their abdominal cavity in pure RIR and their crosses as compared to pure WL breeds. (6) Fertility was sustained for longer in WL than other combinations with post-artificial insemination using constant number of spermatozoa. Fertility after a week of insemination tended to decrease more rapidly than hatchability on a fertile egg basis. (7) It is concluded that both sexes are responsible for the poor fertility in RIR but the female is responsible for poor hatchability and this poor performance is mainly due to greater egg weight loss during incubation.

Animals↗
PubMed2005

Breeding dairy cows for the future in New Zealand.

A brief history of the breeding of dairy cattle in New Zealand is provided. Dairy farming in New Zealand is unique compared with the majority of dairy systems in the developed world. New Zealand has a dependence on grass-based diets and a strict requirement for a 365-day calving interval. Four main areas are discussed: future traits to evaluate, advances in genetic evaluation technologies, impacts of crossbreeding, and future progeny testing schemes. These areas are not independent, e.g. the trend of increasing numbers of crossbred cattle in the national herd will have major impacts on the design of breeding schemes. It is foreseeable that in the future there will be improvements in the national breeding goal to better reflect on-farm profitability, and in the definition of traits and methods of data capture within the national breeding goal. Methods of selection and genetic evaluation that are currently feasible for a small population will become feasible for large populations as computing power improves. Genetic improvement of cows in New Zealand will continue to be a critical component of the increased economic efficiency achieved on dairy farms in this country.

Animals↗
PubMed2005

Olfactory receptor sequence polymorphism within and between breeds of dogs.

Olfactory receptors, to which odorant molecules specifically bind, are encoded by the largest gene family yet identified in the mammalian genome. We investigated additional polymorphism due to the possible existence of multiple alleles dispersed in different dog breeds by carrying out a survey of the sequences of 16 olfactory receptor genes in a sample of 95 dogs of 20 different breeds. The level of polymorphism was high--all genes were found to have allelic variants--leading to amino acid changes and pseudogenization of some alleles in a number of cases. This preliminary study also revealed that some alleles are breed specific (or rare in the dog population), with some representing the major allele in the breeds concerned.

Amino Acid Substitution↗
PubMed1997

Changes in infestation rate and age structure of Dermanyssus hirundinis and Ornithonyssus sylviarum (Acarina) during nidification and breeding period of penduline tit.

Populations of 2 parasitic mites, Dermanyssus hirundinis (Hermann) (63,169 collected individuals) and Ornithonyssus sylviarum (Canestrini et Fanzago) (3,425 collected individuals), in 305 penduline tit, Remiz pendulinus L., nests were studied in 1993 and 1994. The nests were divided into 4 groups: nests without eggs, nests with eggs, nests with nestlings, and nests just after fledging. The average percentage of infested nests increased from the nests without eggs to the nests after fledging (at 20% in both years of investigation), and the increase of mite abundance was exponential. Presence of nestlings in the nests stimulated intensive reproduction of parasitic mites. An increasing infestation intensity in nests was observed during the host breeding period. The 2 mite species exhibited similar age structure patterns in the nests of all the groups and during the entire penduline tit breeding period as well. A decrease in the proportion of adult mites (mainly females) and an increase of nymphs (above all of protonymphs) occurred at the time of fledging and at the end of host breeding period. The percentage of the ovigerous females increased in the individual nests, but decreased during the breeding period of penduline tit. The quantitative parameters of D. hirundinis populations in the highly infested nests depended on the individual nidification and nidobiology of the host, whereas the qualitative parameters (age structure) of these populations depended more on abiotic factors and life strategy of the ectoparasite.

Animals↗
PubMed2002

Breeding strategies for biofortified staple plant foods to reduce micronutrient malnutrition globally.

One sustainable agricultural approach to reducing micronutrient malnutrition among people at highest risk (i.e., resource-poor women, infants and children) globally is to enrich major staple food crops (e.g., rice, wheat, maize, beans and cassava) with micronutrients through plant-breeding strategies. These target groups are dependent on these staples for their sustenance. Available research has demonstrated that micronutrient-enrichment traits are available within the genomes of these major staple food crops that could allow for substantial increases in the levels of Fe, Zn and provitamin A carotenoids (as well as other nutrients and health-promoting factors) without negatively impacting crop yield. Furthermore, Fe- and Zn-dense seeds can increase crop yields when sowed to soils deficient in these nutrients ensuring their adoption by farmers in these regions once they are developed. Importantly, micronutrient bioavailability issues must be addressed when using a plant-breeding approach to eliminating micronutrient malnutrition. The reduction of antinutrient substances that inhibit micronutrient bioavailability or the increase in substances that promote micronutrient bioavailability from staple plant foods are both options that could be pursued in breeding programs, although care needs to be taken not to compromise agronomic performance and sufficient attention paid to possible beneficial roles of compounds which reduce the bioavailability of trace minerals. The time has come to invest in agricultural technologies to find sustainable solutions to micronutrient malnutrition. Plant breeding is one such technology that should be adopted by the world's agricultural community and that should be supported by the world's nutrition and health communities.

Agriculture↗
PubMed2002

Progress in breeding for trace minerals in staple crops.

Staples are not considered an important source of minerals in the diet. However, because of high staple consumption, any increase in mineral concentration might well have a significant effect on human nutrition and health. The nutritional quality of staple crops (rice, cassava, wheat, maize and beans) can be improved by breeding. Studies have shown the potential to exploit the genetic variation in seed concentration of iron and other minerals without the general negative effect on yield of adding new traits. The relationship between yield and mineral concentration may be positive, particularly in mineral-deficient soil. Initial evaluations have shown that some crop varieties have high Fe, Zn and carotene in their edible portions. The next step for conventional breeding will be to study the genetics of trace mineral inheritance to determine the best selection technique. Initial investigations of the genetics for high iron in rice have indicated a complex mode of inheritance, demonstrating additive and dominant gene and environmental effects. Breeding strategies have been developed based on these genetic findings. The use of biotechnological tools, such as molecular marker-assisted selection, will significantly increase the pace and prospects of success for breeding to improve the nutritional value of staple food crops.

Agriculture↗
PubMed1997

The hypostatic genotype of the recessive white prat breed of chickens.

The genetics of the plumage color of the White Prat breed of chicken was studied. Results of crosses between the White Prat breed and Recessive Wheaten (ey/ey) tester line, and Buff Prat (eWh/eWh Co/Co) or Castellana (E/E) breeds, suggested that the former carries the buttercup allele (ebc) at the E-locus, the columbian restriction gene (Co), and the autosomal recessive white (c) gene. Heterozygous Co/co+ in the presence of ebc resulted in a modified stripe pattern in the chick down. The ground color was very dark tan, whereas the light back stripes and the broken head stripe were similar to those of buttercup chicks. Adults were typical buff columbian with considerable black markings on the feathers. The homozygous ebc/ebc Co/Co produced chicks with a black back and a brown head, similar to those previously described for the interaction between Co and the brown (eb) allele. The presence of the recessive white gene masked unexpected genetic variation at the E-locus in the Prat breed, the Buff variety carrying the dominant wheaten (eWh) instead of the buttercup allele. The sex-linked gold (s+) allele was the most frequent in the White Prat variety. The silver (S), sex-linked barring (B), blue (Bl), and possibly dominant white (I) alleles also were present at low frequencies.

Alleles↗
PubMed1997

Relationships between storage and secretion of hepatic lipids in two breeds of geese with different susceptibility to liver steatosis.

Susceptibility to liver steatosis was studied in Landes and Poland geese, which are hyper- and hyporesponsive, respectively, to overfeeding. Plasma lipoproteins were characterized at different stages of the overfeeding process, whereas fatty liver composition was determined after completion of overfeeding and slaughtering. Before overfeeding, plasma lipoprotein profile was typical of birds in both breeds, except that very low density lipoproteins (VLDL) were low in triglyceride (approximately 30%). Moreover, high-density lipoprotein (HDL) concentration was higher in the Poland geese (6.44 vs 4.97 g/L). During overfeeding, hepatic lipogenesis was increased, and fatty liver resulted from accumulation of primarily triglyceride (approximately 95% of lipid content), but also of all other lipids. This accumulation was significantly greater in the Landes geese for all lipids but phospholipid. Thus, the liver weight was 100% higher in this breed (1,005 g vs 485 g), whereas lipid release during sterilization was twofold higher (26.3 vs 7.5%). Parallel, plasma concentration and triglyceride content of hepatic lipoproteins, VLDL and HDL, increased about one- to twofold, this effect being greater in the Poland geese. Therefore, channeling of triglyceride towards secretion rather than in situ storage may be responsible for the hyporesponsiveness of this breed to overfeeding. In both breeds, and especially in the Landes geese, a relative deficiency in phospholipid synthesis together with an enhanced secretion may be limiting factors of hepatocyte hypertrophia and, therefore, of steatosis.

Animals↗
PubMed1998

Genetic diversity of commercial turkey primary breeding lines as estimated by DNA fingerprinting.

The genetic diversity of primary breeding sire and dam lines from the three largest turkey breeders was estimated by band sharing of DNA fingerprints and by genetic distance estimated from band sharing. For comparison, experimental lines selected for increased egg production (E line) or increased 16-wk body weight (F line) were also included in the analysis. Eighteen individual DNA samples per line were digested with HaeIII restriction enzyme and hybridized with Jeffreys' 33.6 probe. The DNA fingerprints were analyzed with computer programs designed to measure band sharing. Within commercial lines, band sharing ranged from 0.370 to 0.508 and was greater in commercial sire lines (average = 0.475) than in commercial dam lines (average = 0.393), indicating that accumulated inbreeding was greater in the sire lines. Band sharing in the F and E lines was 0.479 and 0.522, respectively. The average band sharing among lines was higher for primary breeding sire lines (average = 0.267) than for primary breeding dam lines (0.207), suggesting more genetic diversity in the dam lines. Genetic distance estimated from band sharing was greater among commercial dam lines than commercial sire lines. Based on band sharing between lines and genetic distance estimates, it appears that the experimental E and F lines contain genetic variation not found in the commercial lines. The results of the present study, along with data published in the literature, suggest that commercial primary breeding turkey lines are as diverse, if not more diverse, than similar commercial chicken lines.

Animals↗
PubMed2002

Effects of housing type and breeding system on the reproductive capacity of the red-legged partridge (Alectoris rufa).

Current methods of intensive breeding of the red-legged partridge (Alectoris rufa) are based on "industrial" laying practices, including removal and artificial incubation of eggs. These procedures can alter the reproductive behavior and physiology of the birds and, therefore, may not be suitable for use in breeding programs designed to increase wild populations. This study aimed to determine the effects of intensive housing and breeding methods on the laying capacity and reproductive behavior of the red-legged partridge. In Experiment 1, 70 pairs from a commercial game farm were randomly allocated into three treatment groups and placed in differing designs of breeding cages: 8 m2 cages with solid sides (n = 30), 4 m2 cages with solid sides (n = 30), and 4 m2 cages with mesh sides (n = 10). The number of eggs laid was recorded each week. In Experiment 2, 30 pairs, placed in 30 closed 8 m2 cages, were used. Fifteen pairs were birds reared under the intensive system used on game farms, and the other 15 pairs were birds adopted by pairs of foster parents when they were less than 48 h old. The total number of eggs laid during the reproductive period was recorded. In Experiment 1, egg production was greater in pairs housed in 8 m2 cages. There were no differences in egg production between birds housed in closed or open 4 m2 cages. In Experiment 2, the rearing method did not affect egg production. In both experiments, regardless of rearing history or cage type, the numbers of eggs laid were considerably higher than published figures for wild red-legged partridges. This fact, together with the absence of incubation by 100% of the females, indicates the considerable physiological and behavioral modifications that red-legged partridges have undergone due to domestication.

Animals↗
PubMed2007

Differential estradiol requirement for the induction of estrus behavior and the luteinizing hormone surge in two breeds of sheep.

For a better understanding of the mechanisms that lead to the preovulatory GnRH/LH surge and estrus behavior, the minimum estradiol (E) requirements (dose and duration) to induce each of these events were determined and compared between two breeds of ewes having either single (Ile de France) or multiple (Romanov) ovulations. The ewes were initially studied during a natural estrus cycle, and were then ovariectomized and run through successive artificial estrus cycles. For these artificial cycles the duration and amplitude of the follucular phase E increase were manipulated by E implants. Under all conditions, the onset of estrus behavior was similar in the two breeds, although its duration was longer in Romanov ewes. While a moderate E signal (6 cm for 12 h) induced an LH surge in 10/10 Ile de France ewes, a larger E signal (12 cm for 12 h) was minimally effective in Romanov ewes (4/10). Additional studies revealed that a small E signal (3 cm for 6 h) induced full estrus behavior in all Romanov ewes but was completely ineffective in Ile de France animals (0/10). Higher doses and mostly longer durations of the E signal (12 cm for 24 h) were required to induce a surge in all the Romanov ewes. These results demonstrate a clear difference in the E requirement for the induction of estrus behavior and the LH surge between breeds of ewes that have different ovulation rates. These data provide compelling evidence that, in one breed, the neuronal systems that regulate both events require different estrogen signals.

Animals↗
PubMed2001

Offspring body condition and immunocompetence are negatively affected by high breeding densities in a colonial seabird: a multiscale approach.

Why avian colonies vary in size and how food competition among nearby colonies affects offspring quality are still not completely understood. We simultaneously examined the effects of four scales of breeding density on two measures of offspring viability (body condition and T-cell-mediated immunity) in the colonial Magellanic penguin. Body condition of fledglings was inversely correlated with breeding density within 100 m(2) of nests, and decreased with increasing numbers of breeding pairs competing within the parental foraging ranges (100 km), probably as a result of density-dependent food depletion. The T-cell-mediated immune response was positively correlated with body condition, reflecting, to some extent, the previous breeding-density effects, and was negatively correlated with colony size, which may be related to social stress. However, given the effect of protein intake on cell immunity, this result could also indicate a thus far neglected cost of coloniality, namely the consumption of low-protein food to compensate for the depletion of optimal prey. These results were not influenced by other traits, nor by the current exposure of birds to parasites and diseases, as measured by serological variables. Since body condition and the T-cell-mediated immune response of fledgling birds are indicators of their survival and recruitment prospects, the costs we have identified can explain variability in colony size in relation to food competition with surrounding colonies, as well as the skewed distribution toward small colonies in this species.

Animals↗
PubMed2005

Genotype-level variation in lifetime breeding success, litter size and survival of sheep in scrapie-affected flocks.

Five different sheep flocks with natural outbreaks of scrapie were examined to determine associations between individual performance (lifetime breeding success, litter size and survival) and scrapie infection or PrP genotype. Despite different breed composition and forces of infection, consistent patterns were found among the flocks. Regardless of the flock, scrapie-infected sheep produced on average 34 % fewer offspring than non-scrapie-infected sheep. The effect of scrapie on lifetime breeding success appears to be a function of lifespan as opposed to fecundity. Analysis of litter size revealed no overall or genotype differences among the five sheep flocks. Survival, however, depends on the individual's scrapie status (infected or not) and its PrP genotype. Susceptible genotypes appear to perform less well in lifetime breeding success and life expectancy even if they are never affected with clinical scrapie. One possible explanation for these results is the effect of pre-clinical scrapie. Additional evidence supporting this hypothesis is discussed.

Animals↗
PubMed2002

Stability and instability of polymorphic populations and the role of multiple breeding seasons in phase III of Wright's shifting balance theory.

It is generally difficult for a large population at a fitness peak to acquire the genotypes of a higher peak, because the intermediates produced by allelic recombination between types at different peaks are of lower fitness. In his shifting-balance theory, Wright proposed that fitter genotypes could, however, become fixed in small isolated demes by means of random genetic fluctuations. These demes would then try to spread their genome to nearby demes by migration of their individuals. The resulting polymorphism, the coexistence of individuals with different genotypes, would give the invaded demes a chance to move up to a higher fitness peak. This last step of the process, namely, the invasion of lower fitness demes by higher fitness genotypes, is known as phase III of Wright's theory. Here we study the invasion process from the point of view of the stability of polymorphic populations. Invasion occurs when the polymorphic equilibrium, established at low migration rates, becomes unstable. We show that the instability threshold depends sensitively on the average number of breeding seasons of individuals. Iteroparous species (with many breeding seasons) have lower thresholds than semelparous species (with a single breeding season). By studying a particular simple model, we are able to provide analytical estimates of the migration threshold as a function of the number of breeding seasons. Once the threshold is crossed and polymorphism becomes unstable, any imbalance between the different demes is sufficient for invasion to occur. The outcome of the invasion, however, depends on many parameters, not only on fitness. Differences in fitness, site capacities, relative migration rates, and initial conditions, all contribute to determine which genotype invades successfully. Contrary to the original perspective of Wright's theory for continuous fitness improvement, our results show that both upgrading to higher fitness peaks and downgrading to lower peaks are possible.

Algorithms↗
PubMed1990

Associations between blood groups, blood protein polymorphisms and breeding values for production traits in Swedish Red and White Dairy bulls.

The relationships of nine blood group systems and two blood protein polymorphisms with breeding values for several production traits were examined in dairy cattle of the Swedish Red and White (SRB) breed. The material consisted of 2212 bulls; the bulls were performance tested for growth rate and their breeding values for milk yield, fat and protein content in milk were estimated from progeny tests. The direct effect of marker alleles or marker phenotypes was analysed in a multiple regression model. Several significant associations were found; many supported earlier findings. However, the contribution of the markers to the total variation of the breeding values was very small. Linkage between marker loci and production loci was studied in offspring from heterozygous sires by estimating the interactions between sire and marker alle using a model eliminating the direct effects of sire and marker alle. There were strong indications of linkage between some marker loci (e.g. B, J and Am-1 loci) and loci with large effects on production traits.

Alleles↗
PubMed2006

Ecological constraints on breeding system evolution: the influence of habitat on brood desertion in Kentish plover.

1. One of the fundamental insights of behavioural ecology is that resources influence breeding systems. For instance, when food resources are plenty, one parent is able to care for the young on its own, so that the other parent can desert and became polygamous. We investigated this hypothesis in the context of classical polyandry when females may have several mates within a single breeding season, and parental duties are carried out largely by the male. 2. We studied a precocial wader, the Kentish plover Charadrius alexandrinus, that exhibits variable brood care such that the chicks may be raised by both parents, only by the female or, more often, only by the male. The timing of female desertion varies: some females desert their brood at hatching of the eggs and lay a clutch for a new mate, whereas other females stay with their brood until the chicks fledge. Kentish plovers are excellent organisms with which to study breeding system evolution, as some of their close relatives exhibit classical polyandry (Eurasian dotterel Eudromias morinellus, mountain plover Charadrius montanus), whereas others are polygynous (northern lapwing Vanellus vanellus). 3. Kentish plovers raised their broods in two habitats in our study site in southern Turkey: saltmarsh and lakeshore. Food intake was higher on the lakeshore than in the saltmarsh as judged from feeding behaviour of chicks and adults. As the season proceeded and the saltmarsh dried out, the broods moved toward the lakeshore. 4. As the density of plovers increased on lakeshore, the parents spent more time defending their young, and female parents stayed with their brood longer on the lakeshore. 5. We conclude that the influence of food abundance on breeding systems is more complex than currently anticipated. Abundant food resources appear to have profound implications on spatial distribution of broods, and the social interactions between broods constrain female desertion and polyandry.

Animal Feed↗
PubMed1995

Breed differences in the plasma renin activity and plasma aldosterone concentration of dogs.

Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were studied in 90 clinically healthy dogs: 15 Beagles, 15 Cavalier King Charles spaniels (CKCS), 15 Medium Sized Poodles, 15 Labrador retrievers, 15 Irish wolfhounds and 15 Newfoundlands. All dogs were fed a low sodium diet for at least 3 days before blood sampling in a home setting. There was a significant difference between breeds with respect to both PRA (P = 0.0002), PAC (P = 0.002) and PRA/PAC ratio (P < 0.0001). The highest PRA values were found in CKCS and Poodles, two breeds known to be predisposed to chronic valvular disease. Five CKCS had PRA values exceeding 3.0 ng/ml/h while this was the case in only one of the remaining 75 dogs. In contrast to the high PRA values, CKCS had low PAC values, and therefore much higher PRA/PAC ratios than the other breeds. In Irish wolfhounds, both the PRA and PAC values were low. In conclusion, considerable breed differences in PRA and PAC were found in the present study. Further studies are needed to determine if there is an association between developing chronic valvular disease and a high PRA in dogs.

Aldosterone↗