Genetic selection to produce lines of sheep differing in plasma copper concentrations

ABSTRACTMale lambs were selected annually at 18 and 24 weeks of age for high or low concentrations of copper in plasma to produce two closed lines. The difference between the high and low lines increased to approx. 0·5 mg/1 after 5 years when the experiment ended, indicating appreciable additive genetic variation for the concentration of Cu in plasma. The selection lines were derived from a population of Scottish Blackface × Welsh Mountain crosses which had been interbred for many generations. The two parental breeds contributing to the cross normally differ in a number of aspects of Cu status with that of the Welsh higher than that of the Blackface. Both pure breeds were kept as controls. In the final year, Cu concentrations of the high selection line exceeded the values of the Welsh and the low selection line had values below those of the Blackface. Differences between the selection lines persisted at all ages.There were indications of changes in the frequency of the Hb alleles, associated with the selection for Cu concentrations, but there were no correlated changes in body weight, reproductive performance or lamb mortality during the 5-year selection period when dietary supplies of Cu were not particularly restrictive.

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Influence of Genetic Selection for Growth and Broodstock Diet n-3 LC-PUFA Levels on Reproductive Performance of Gilthead Seabream, Sparus aurata

Animals ◽

10.3390/ani11020519 ◽

2021 ◽

Vol 11 (2) ◽

pp. 519

Author(s):

Shajahan Ferosekhan ◽

Serhat Turkmen ◽

Cathaysa Pérez-García ◽

Hanlin Xu ◽

Ana Gómez ◽

...

Keyword(s):

Reproductive Performance ◽

Egg Quality ◽

Sparus Aurata ◽

Genetic Selection ◽

Growth Trait ◽

High Growth ◽

Gilthead Seabream ◽

Commercial Diet ◽

Selection For ◽

Broodstock Diet

Genetic selection in gilthead seabream (GSB), Sparus aurata, has been undertaken to improve the growth, feed efficiency, fillet quality, skeletal deformities and disease resistance, but no study is available to delineate the effect of genetic selection for growth trait on GSB reproductive performance under mass spawning condition. In this study, high growth (HG) or low growth (LG) GSB broodstock were selected to evaluate the sex steroid hormones, sperm, egg quality and reproductive performance under different feeding regime of commercial diet or experimental broodstock diet containing either fish oil (FO) or vegetable oil (VO) based diet. Under commercial diet feeding phase, broodstock selected for either high growth or low growth did not show any significant changes in the egg production per kg female whereas egg viability percentage was positively (p = 0.014) improved by the high growth trait broodstock group. The experimental diet feeding results revealed that both growth trait and dietary fatty acid composition influenced the reproductive performance of GSB broodstock. In the experimental diet feeding phase, we observed high growth trait GSB males produced a higher number of sperm cells (p < 0.001) and also showed a higher sperm motility (p = 0.048) percentage. The viable egg and larval production per spawn per kg female were significantly improved by the broodstock selected for high growth trait and fed with fish oil-based diet. This present study results signifies that gilthead seabream broodstock selected on growth trait could have positive role in improvement of sperm and egg quality to produce viable progeny.

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Effect of dietary-induced increases in circulating insulin concentrations during the early postpartum period on reproductive function in dairy cows

Reproduction ◽

10.1530/rep.0.1230419 ◽

2002 ◽

pp. 419-427 ◽

Cited By ~ 138

Author(s):

JG Gong ◽

WJ Lee ◽

PC Garnsworthy ◽

R Webb

Keyword(s):

Body Weight ◽

Dairy Cows ◽

Milk Yield ◽

Body Condition ◽

Reproductive Performance ◽

Body Condition Score ◽

Post Partum ◽

Dietary Treatment ◽

Genetic Merit ◽

Selection For

Although it has become increasingly clear that fertility in modern dairy cattle is declining in association with increased milk yields, the underlying mechanism is poorly understood. The first ovulation post partum is delayed in dairy cows undergoing selection for genetic merit for milk yield in association with lower circulating insulin concentrations. The aim of this study was to investigate whether feeding a diet to increase circulating insulin concentrations can overcome this delay in the first ovulation post partum. The experiment was a 2 x 2 factorial design (n = 10 per group) involving diet and genetic merit for milk yield. The dietary treatment started on the day of calving and lasted for 50 days. Plasma samples were collected each day and ovarian ultra-sonography was performed three times a week during the experimental feeding period. Milk yield was recorded each day, and body weight and body condition score were determined each week. Milk samples were collected three times a week from day 50 to day 105 post partum, and reproductive performance data were recorded for all the cows as part of the routine farm practice. The dietary treatment induced significant differences in plasma insulin concentrations in both high and low genetic merit cows. Although high genetic merit cows produced more milk, lost more body weight and had lower body condition scores during the experiment, no significant effect of diet was observed on these measurements. The high insulin inducing diet increased the proportion of cows ovulating within 50 days of calving and reduced the intervals from calving to first ovulation, and tended to reduce the intervals from calving to first service and to conception. These fertility parameters were also more favourable in low than in high genetic merit cows, but no interaction between diet and genetic merit was observed for any of these parameters. Genetic merit, but not diet, also affected the number of services required per conception and the conception rate. In conclusion, these results have confirmed that genetic selection for high milk yield is associated with a decrease in reproductive performance in dairy cows. More importantly, this study has demonstrated that it is possible to alleviate this problem by nutritional manipulation.

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The effect of feed restriction on sexual maturity and initial reproductive performance of broiler pullets under different light treatments

Australian Journal of Experimental Agriculture ◽

10.1071/ea9690417 ◽

1969 ◽

Vol 9 (39) ◽

pp. 417 ◽

Cited By ~ 1

Author(s):

RAE Pym ◽

R Sledge

Keyword(s):

Body Weight ◽

Reproductive Performance ◽

Sexual Maturity ◽

Feed Restriction ◽

Restricted Feeding ◽

Egg Weight ◽

Laying Performance ◽

The Mean ◽

The Difference ◽

Lighting Systems

An experiment was conducted to examine the effect of restricted feeding under two lighting systems during the rearing period on the initial laying performance of broiler type pullets. The rearing treatments were imposed at nine weeks of age, removed at 22 weeks and the trial was discontinued at 36 weeks of age. The feeding treatments (restricted versus ad lib.) were arranged factorially with the lighting treatments (decreasing versus increasing). Birds reared on restricted feeding reached sexual maturity 16 days later than full fed birds, ate 17 per cent less feed to 22 weeks and gained seven per cent less in body weight to 24 weeks of age and ten per cent less to 36 weeks. Birds reared under the decreasing lighting regime reached sexual maturity at the same age as those reared under increasing lighting, ate five per cent more feed during the rearing and laying periods and gained five per cent more in body weight to 24 weeks. The mean weight of eggs laid between 24 and 34 weeks of age from pullets subjected concurrently to decreasing lighting and restricted feeding was approximately two grams heavier than that of the other three treatment combinations. Mean egg weight was one gram greater in the restricted than in the full fed group, although the difference was not statistically significant. Laying mortality was lower in the restricted fed group than in the full fed group.

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The effects of litter size, sex, age, body weight, dam age and genetic selection for cold resistance on the physiological responses to cold exposure of scottish blackface lambs in a progressively cooled water bath

Animal Science ◽

10.1017/s0003356100002968 ◽

1987 ◽

Vol 45 (3) ◽

pp. 477-491 ◽

Cited By ~ 13

Author(s):

A. W. Stott ◽

J. Slee

Keyword(s):

Body Weight ◽

Metabolic Rate ◽

Cold Exposure ◽

Cold Resistance ◽

Genetic Selection ◽

Water Bath ◽

Skin Thickness ◽

Selection Line ◽

Unit Body Weight ◽

Total Body

ABSTRACTThe resistance to body cooling of 594 newborn Scottish Blackface lambs was measured in a water bath during a programme of upwards and downwards genetic selection. Cold resistance was defined as the time taken for rectal temperature to fall to 35°C in the water bath.Upwards selection produced increased cold resistance which was genetically associated with increased skin thickness, increased total body insulation and greater persistence of high metabolic rate during cold exposure. The first two correlated responses to selection were more pronounced in twins than in singles.High cold resistance was phenotypically, but not genetically, associated with greater body weight, increased coat depth and higher levels of cold-induced metabolic rate (heat production). Single lambs showed higher weight-adjusted metabolic rates and higher cold resistance than twins. Singles recovered from hypothermia faster than twins in the low selection line only.Female lambs showed higher metabolic rate (whether weight-adjusted or not) and greater total body insulation than males. Their greater cold resistance was not quite significant. Increasing age (range 0·3 to 36 h) was associated with a small but significant decline in cold resistance.Thermoneutral metabolic rate was proportional to body surface area, whereas peak metabolic rate was proportional to body weight such that peak metabolic rate per unit body weight was independent of changes in body weight. These findings are discussed in relation to lamb survival.

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Changes in muscle cell cation regulation and meat quality traits are associated with genetic selection for high body weight and meat yield in broiler chickens

Genetics Selection Evolution ◽

10.1186/1297-9686-41-8 ◽

2009 ◽

Vol 41 (1) ◽

pp. 8 ◽

Cited By ~ 22

Author(s):

Dale A Sandercock ◽

Zoe E Barker ◽

Malcolm A Mitchell ◽

Paul M Hocking

Keyword(s):

Body Weight ◽

Meat Quality ◽

Muscle Cell ◽

Broiler Chickens ◽

Genetic Selection ◽

Quality Traits ◽

Meat Yield ◽

High Body ◽

Meat Quality Traits ◽

Selection For

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Selection for fertility in Australian Merino sheep

Australian Journal of Agricultural Research ◽

10.1071/ar9630460 ◽

1963 ◽

Vol 14 (4) ◽

pp. 460 ◽

Cited By ~ 32

Author(s):

SSY Young ◽

HN Turner ◽

CHS Dolling

Keyword(s):

Body Weight ◽

Genetic Correlations ◽

Fibre Diameter ◽

Likelihood Method ◽

Mass Selection ◽

Genetic Progress ◽

Subsequent Performance ◽

Fertility Trait ◽

Selection For ◽

The Difference

Phenotypic and genetic parameters for fertility in sheep, in terms of number of lambs born and number weaned, have been estimated in a flock of medium Peppin Merinos. Repeatability of fertility traits over all ages is low, but there is an age effect, the record at 3 years of age having a higher value than those at 2 or 4 years. The regression of subsequent performance on a difference of 1 lamb at the initial lambing was higher for the difference between 1 and 2 lambs than between 0 and 1 lamb, which indicated that selection for twins is likely to raise fertility in the current flock more rapidly than selection against barrenness. The estimate of heritability for 2 years of age was negligible for each fertility trait, but the estimates for the 3-year-old record were higher, the value for lambs born being over 0.3. Mass selection for number of lambs born at 3 years of age would thus be expected to lead to appreciable genetic progress, while there would be at least some progress in number of lambs weaned. Phenotypic and genetic correlations were also estimated between fertility at different ages and 10 sheep and wool traits measured at 15–16 months of age. Phenotypically, fertility is positively correlated with body weight and negatively with skin wrinkle score. Genetically, it is suggested from the estimates that fertility is positively correlated with body weight and staple length and negatively correlated with fibre diameter, clean scoured yield, and wrinkle score. No phenotypic or genetic correlation was found between greasy or clean wool weight and either measure of fertility. The application of the findings to breeding for higher fertility is discussed. In an appendix, a maximum likelihood method of estimating heritability for all-or-none traits in half-sib data is presented.

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Non-random X-chromosome inactivation in the mouse: difference of reaction to imprinting

Genetics Research ◽

10.1017/s0016672300020930 ◽

1982 ◽

Vol 39 (3) ◽

pp. 237-259 ◽

Cited By ~ 9

Author(s):

D. S. Falconer ◽

J. H. Isaacson ◽

I. K. Gauld

Keyword(s):

Genetic Variation ◽

Chromosome Inactivation ◽

Enzyme Assays ◽

Linked Gene ◽

Percentage Points ◽

High Line ◽

Liver And Kidney ◽

Selection For ◽

The Difference ◽

Activation Probability

SummarySelection for increased and for decreased expression of the sex-linked gene brindled (Mobr) in heterozygous females produced two lines with non-random X chromosome inactivation. In the High line the X chromosome marked by brindled was active in about 60% of cells, while in the Low line it was active in about 25% of cells. The whole of the difference was caused by the chromosomes carrying brindled: neither the unmarked X chromosome nor the autosomes were differentiated. There was a positive correlation between the expression of brindled in daughters and mothers. This was probably not caused by residual genetic variation, but was more probably a maternal effect similar to that described by Cattanach & Papworth (1981). On this assumption the daughters' scores were adjusted to a standard maternal score. Enzyme assays on females doubly heterozygous for brindled and for the sex-linked Pgk-1 locus proved that the percentage of brindled in the coat provided an accurate measure of the X-inactivation proportions in the blood, liver and kidney. The accuracy was improved by adjustment for maternal score. In the selection lines, brindled was always inherited from the mother. When brindled was transmitted by male parents the probability of activation of its chromosome was increased by 8 percentage points in the High line and 18 in the Low line. This effect of the parental source is much greater than has previously been reported. The responses to selection can be interpreted in terms of the Xce locus controlling the activation probability, different alleles on the chromosomes carrying brindled being selected in the two lines. If this interpretation is correct, the alleles on one or both of the chromosomes carrying brindled were different from any of the three known alleles. The different effects of male transmission in the two lines can be described as a difference between the two chromosomes in their reactions to imprinting. This difference might possibly also be due to the Xce locus.

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Identification of Genes Targeted in South African Merino and Afrino Sheep Populations Under Long-Term Selection for Reproduction and Body Weight

10.21203/rs.3.rs-128951/v1 ◽

2020 ◽

Author(s):

Margaretha Snyman ◽

Sunika Süllwald ◽

Willem Olivier ◽

Carina Visser

Keyword(s):

Body Weight ◽

South African ◽

Reproductive Performance ◽

Genome Wide Association Study ◽

Growth Traits ◽

Reproductive Traits ◽

Term Selection ◽

A Genome ◽

Selection For

Abstract Background: Reproductive performance and body weight are of the utmost economic importance in determining the efficiency of sheep production. Simultaneous selection for increased reproductive performance and early growth traits is a common strategy in many flocks, but ambiguous results regarding the relationship between reproduction and body weight have been reported. The objective of this study was to perform a genome-wide association study (GWAS) in two South African Merino flocks and an Afrino sheep flock that were selected for both reproduction and body weight over decades. The GWAS aimed to identify SNPs associated with genes affecting the traits number of lambs born (NLB), number of lambs weaned (NLW), total weight of lamb weaned (TWW) and body weight (BW) and thus to ascertain which genes were targeted through directional selection.Results: In the GWAS, 16 SNP markers associated with reproductive traits were identified among the three populations, while 15 SNPs were associated with body weight. These SNPs were linked respectively to 26 and 21 documented genes in the sheep genome. Most of these genes were previously associated in literature with reproduction related, as well as with growth related traits in various farm animal species. This study, supported by results from previous studies performed on sheep and cattle, identified the following genes that warrant further investigation as to their functions and processes relating to growth and reproduction in sheep: MAP7D1, TRAPPC3, THRAP3, TRMP8, SPP2, HDAC9, ZFHX3, SIX6, C14orf39, TAF4B, TRSP1 EYA2, RBMS3, STL38L, BSPH1, LIG1, CABP5 and ELSPBP1. Conclusions: Long-term selection in the flocks for both body weight and reproductive traits, and especially on the composite trait TWW, have favoured genes with pleiotropic effects influencing both groups of traits. SNPs associated with these pleiotropic genes were detected in the association analyses for the various traits.

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