Serving capacity and scrotal circumference of ram lambs as affected by selection for reproductive rate

1992 ◽  
Vol 9 (1) ◽  
pp. 61-68 ◽  
Author(s):  
P.J. Burfening ◽  
D. Rossi
Keyword(s):  
Reproductive Rate ◽  
Scrotal Circumference ◽  
Ram Lambs ◽  
Selection For

Genetic selection for cold resistance in Scottish Blackface lambs

1986 ◽  
Vol 43 (3) ◽  
pp. 397-404 ◽  
Author(s):  
J. Slee ◽  
A. W. Stott
Keyword(s):  
Cold Resistance ◽  
Selection Process ◽  
Genetic Selection ◽  
Resistance Rate ◽  
Realized Heritability ◽  
Resistance Response ◽  
Rate Of Recovery ◽  
Ram Lambs ◽  
Selection For ◽  
Time Required

ABSTRACTHypothermia with starvation is a major cause of neonatal mortality among lambs born outdoors. The results of selection for resistance to hypothermia (cold resistance) in newborn Scottish Blackface lambs are described. Cold resistance was defined as the time required to induce a decline in body temperature of about 4·5°C by means of tests involving part-immersion in a cooled water bath. From about 200 tested lambs (half males) four ram lambs with the lowest cold resistance and four with the highest resistance were selected and each mated randomly at 7 months of age to about 30 ewes to establish upward and downward selection lines. The progeny were subsequently tested for cold resistance and the selection process was repeated for four male generations. Tested females were allocated at 18 months of age to high or low lines according to their performance as lambs.Preliminary half-sib analysis and sire-offspring regression gave estimates of 0·3 for the heritability of cold resistance. Response to selection was rapid but asymmetrical with a realized heritability for cold resistance of 0·27 (s.e. 0·13) for upward selection, 0·01 (s.e. 0·16) for downward selection and 0·17 (s.e. 0·09) for the line divergence.Body weight at test was phenotypically, but not genetically, correlated with cold resistance. Rate of recovery from induced hypothermia was not significantly correlated with cold resistance. The results are discussed in relation to lamb mortality in the field.

Selection for cow lifetime pregnancy rate using bull and heifer growth and reproductive traits in composite cattle

2000 ◽  
Vol 80 (3) ◽  
pp. 507-510 ◽  
Author(s):  
P. B. Mwansa ◽  
R. A. Kemp ◽  
D. H. Crews Jr ◽  
J. P. Kastelic ◽  
D. R. C. Bailey ◽  
...  
Keyword(s):  
Birth Weight ◽  
Key Words ◽  
Pregnancy Rate ◽  
Growth Traits ◽  
Genetic Correlations ◽  
Reproductive Traits ◽  
Genetic Change ◽  
Direct Selection ◽  
Scrotal Circumference ◽  
Selection For

Genetic correlations of lifetime pregnancy rate with bull and heifer growth and reproductive traits in a beef composite population were estimated. Yearling scrotal circumference had an unfavorable genetic correlation (rg = −0.25) while yearling tonometer score was favorably related (rg = 0.22) to lifetime pregnancy rate. Heifer pregnancy rate, birth weight, weaning weight, yearling weight and age at puberty in heifers had significant genetic correlations (rg = 0.97, 0.58, 0.57, 0.33 and −0.21, respectively) with lifetime pregnancy rate. Lifetime pregnancy rate may be successfully predicted by easy-to-measure heifer growth traits. Using indices including scrotal and heifer growth traits, annual genetic change in lifetime pregnancy rate may be increased 3.1 times compared with direct selection. Key words: Scrotal circumference, tonometer, pregnancy, reproduction, puberty

scholarly journals Characteristics of the puberty in hair ram lambs and its crosses in a non-seasonal country

2018 ◽  
pp. 7097-7103
Author(s):  
Liliana Chacón ◽  
Harvey Lozano Marquez ◽  
Jaumer Andrés Orozco Clavijo ◽  
Ariosto Ardila Silva
Keyword(s):  
Semen Quality ◽  
Serum Testosterone ◽  
Elisa Test ◽  
Minimum Concentration ◽  
Scrotal Circumference ◽  
Genotype Effect ◽  
Body Development ◽  
Tropical Conditions ◽  
Ram Lambs ◽  
Santa Inês

Objective. Aimed to describe the characteristics of the onset of puberty in males in Colombian hair ram lambs (Ovino de Pelo Colombiano, OPC), and their crosses with Katahdin and Santa Inés sheep in a farm located in Villavicencio, Meta. Materials and methods. 15 lambs of three biotypes: OPC x OPC, Santa Ines x OPC (SO) and Katahdin X OPC (KO) from four months of age, five per group. Ram lambs were grazing and they had supplementation with commercial salt and water ad libitum. Monthly body weight, testicular measurement, scrotal circumference (CE) were measured and serum testosterone were determined by Elisa test, an ultrasound of the two testicles was performed to determine the presence of the testicular mediastinum, also evaluating the presence and detachment of the urethral prolongation and then electro ejaculation was performed to determine the macroscopic and microscopic characteristics of the semen. Results. Genotype effect was significant for evolution of body development (BW, SC, TV) over time, Santa Ines and Katahdin crosses presented the highest values in BW during the investigation whereas OPC lambs maintained a lower value until the end of the trial. At least four evaluations were made in the males or until the presentation of a minimum concentration of 150 million of sperm per ml with 30% of individual progressive motility.  Conclusions.Around six months old is the puberty onset for ram lambs under tropical conditions, in a non-seasonal country, based on a diversity of variables including body development, semen quality, and testosterone levels among others.

scholarly journals Die gebruik van anaboliese steroïede by ramlammers

1993 ◽  
Vol 12 (1) ◽  
pp. 5-7
Author(s):  
J. P. C. Greyling
Keyword(s):  
Body Weight ◽  
Body Length ◽  
Anabolic Steroids ◽  
Serum Testosterone ◽  
Treated Group ◽  
Scrotal Circumference ◽  
Group A ◽  
The Mean ◽  
Ram Lambs ◽  
Body Parameters

The effect of anabolic steroids on certain body parameters in ram lambs was investigated. Twenty Ile de France ram lambs were allocated at random to two groups after weaning (3 months). One group (n = 10) was treated weekly with an intramuscular injection of an anabolic steroid (50 mg nandrolone laurate)for a 12-week period. The second group (n = 10) served as a control. Parameters recorded weekly included scrotal circumference, scrotal volume, shoulder width, body length, shoulder height, body weight and serum testosterone concentration. Treatment with steroids did not significantly increase the mean shoulder width (22,8 vs 22,0 cm), shoulder height (61,7 vs. 60.8 cm), body length (72,8 vs. 70,2 cm) or body weight (42,5 vs. 39,8 kg). Scrotal circumference and volume were significantly (P <0,01) less in the treated group - a decrease of 24,5% and 51,2%. respectively.

Selection for a moderately insecticide resistant clone of Myzus persicae (Hemiptera: Aphididae) on sugarbeet in the absence of pesticides

1998 ◽  
Vol 88 (6) ◽  
pp. 653-658 ◽  
Author(s):  
I.S. Williams ◽  
L.A. Haylock ◽  
A.M. Dewar ◽  
A.F.G. Dixon
Keyword(s):  
Myzus Persicae ◽  
Reproductive Rate ◽  
Lower Mortality ◽  
Resistant Clone ◽  
Significant Difference ◽  
Selection For ◽  
Moderately Resistant

AbstractHighly resistant and extremely resistant clones (R2 and R3) of Myzus persicae (Sulzer) exhibited a significantly lower mortality and developed a deleterious dark stomach deposit less frequently on sugarbeet than a susceptible (S) clone. After allowing equal populations of four resistant clones to develop together on sugarbeet for four weeks, approximately half of the aphids recovered were from the moderately resistant (R1) clone, suggesting that this clone had a significantly greater reproductive rate than the others. There was no significant difference in the propensity of any clone to produce alates on sugarbeet, although none of the clones produced very many. It is suggested that, even in the absence of insecticides on sugarbeet, resistant clones may become dominant due to their higher fecundity (R1 clones) and lower mortality (R2 and R3 clones) than susceptible clones.

Genetic improvement of feed efficiency of beef cattle: what lessons can be learnt from other species?

2004 ◽  
Vol 44 (5) ◽  
pp. 371 ◽  
Author(s):  
W. S. Pitchford
Keyword(s):  
Beef Cattle ◽  
Heat Loss ◽  
Feed Efficiency ◽  
Production Systems ◽  
Reproductive Rate ◽  
Production Traits ◽  
Beef Industry ◽  
Marker Test ◽  
Pregnancy And Lactation ◽  
Selection For

About half of the feed in beef production systems is used to maintain the breeding herd. Of the remaining 50%, about 20% is used by the breeding cow for pregnancy and lactation and 30% is used by the growing calf. There seems little opportunity to improve efficiency of production (lactation and growth) but reasonable opportunity to increase maintenance efficiency. The mean heritability of net feed efficiency from 35 estimates across 7 species/types was 0.25 ± 0.02. Unfortunately, the genetic correlation between net feed efficiency in young bulls and mature cows is likely to be significantly less than 1, thus responding slowly to selection.While it seems clear that improvements in maintenance efficiency can be made, they may come at a cost. In poultry and mice, increased net feed efficiency has been associated with increased fatness but in pigs and beef cattle there is some evidence of the reverse. While a number of studies have predicted that selection for efficiency may result in lower proportions of crucial, metabolically active visceral organ tissues, there are few studies to support this.Poultry and mouse studies both clearly show that increased net feed efficiency is associated with decreased heat production. This decrease is due to both decreased cost of digestion (heat loss) and decreased activity. In poultry, this decreased heat loss resulted in the more efficient line being more affected by high temperatures. Also, it is possible that at low temperatures, the differences in efficiency may not exist. At this stage it is not clear if the decreased activity is an adaptive advantage or disadvantage. In mice and possibly also pigs and poultry, increased net feed efficiency has been associated with a decreased reproductive rate measured as litter size or egg number. This should definitely be of concern when embarking on selection for improved net feed efficiency in the beef industry. It is recommended that since feed intake is both difficult and expensive to measure, a gene or marker test should be developed, and correlated effects on a range of production traits be carefully evaluated.

Reproductive performance of ewe lambs: genetic correlation with weaning weight and subsequent reproductive performance

1976 ◽  
Vol 16 (80) ◽  
pp. 321 ◽  
Author(s):  
R Barlow ◽  
CJ Hodges
Keyword(s):  
Genetic Correlation ◽  
Reproductive Performance ◽  
Agricultural Research ◽  
Reproductive Rate ◽  
Research Station ◽  
Weaning Weight ◽  
Net Reproductive Rate ◽  
Ewe Lambs ◽  
Ewe Lamb ◽  
Selection For

The reproductive performance of Merino ewe lambs was examined in flocks with different selection histories for growth to weaning and net reproductive rate. These ewes were drawn from selection flocks maintained at the Agricultural Research Station, Trangie. There was evidence of a positive genetic correlation between weaning weight and reproductive performance of ewe lambs. Selection for weaning weight had a significant effect on the percentage of ewes lambing (P < 0.05). This appeared to be a function of a higher level of fertility (P <0.05) and a higher proportion of ewes mating (n.s.). The proportion of ewes apparently in oestrus during a 39 day teasing period, prior to joining, was significantly influenced by selection for weaning weight (P < 0.05). Simultaneous selection for increased net reproductive rate, weaning weight and clean fleece weight did not result in higher ewe lamb performance than that achieved by selection for increased weaning weight alone. No conclusion could be drawn from these data about the correlation between net reproductive rate and reproductive performance of ewe lambs.

Genetic relations and indirect response to selection based on indices for scrotal circumference, visual scores and weight gain in beef cattle

2018 ◽  
Vol 58 (7) ◽  
pp. 1210 ◽  
Author(s):  
A. A. Boligon ◽  
P. P. Farias ◽  
V. M. Roso ◽  
M. L. Santana ◽  
A. B. Bignardi ◽  
...  
Keyword(s):  
Weight Gain ◽  
Beef Cattle ◽  
Selection Process ◽  
Selection Index ◽  
Genetic Correlations ◽  
Correlated Response ◽  
Indirect Response ◽  
Genetic Gains ◽  
Scrotal Circumference ◽  
Selection For

Genetic improvement in beef cattle involves evaluation for fertility, growth, carcass and visual scores traits. In general, genetic and economic parameters of these traits are considered for selection index construction. The present study was conducted to establish the magnitude of genetic and phenotypic correlations between visual scores of conformation, precocity and muscling at weaning and at yearling, birth to weaning weight gain, weaning to yearling weight gain and yearling scrotal circumference, and between these traits with selection indices applied in this population. In addition, the expected gains were obtained in such traits by taking under consideration the adopted selection criteria based on indices. Positive and high genetic correlations were estimated between weaning traits (visual scores and weight gain), ranging from 0.70 ± 0.02 to 0.97 ± 0.01. In genetic terms, the same visual scores, but evaluated in two ages (weaning and yearling) showed positive and high associations, with values of 0.90 ± 0.01 (conformation), 0.88 ± 0.01 (precocity) and 0.84 ± 0.02 (muscling). Genetic associations between yearling visual scores with scrotal circumference and weaning to yearling weight gain ranging from 0.36 ± 0.02 to 0.53 ± 0.01. Using the weaning index, are expected genetic gains ranging from 0.26% to 0.70%/year of the phenotypic mean of each weaning trait. Using the yearling index, annual genetic gains estimated for weaning traits (ranging from 0.25% to 0.63% of the phenotypic mean of the trait) were lower than that obtained at yearling (ranging from 0.27% to 0.98% of the phenotypic mean of the trait). Selection for one of traits obtained at weaning should result, by correlated response, in gain for the others. Also, the choice of animals with higher breeding values for weaning visual scores, beyond anticipate the selection process, should lead to favourable changes in these traits at yearling. Selection for better body composition at yearling (higher scores) should provide increase in scrotal circumference and weight gain. The use of higher values of the indices should result in positively correlated response, but in different magnitudes for each trait used in these indices. However, in both weaning and yearling, higher genetic gains to visual scores are expected in the same period, when the selection is based on the values of these indices.

The performance of the Border Leicester in Australia

2021 ◽  
Vol 61 (1) ◽  
pp. 1
Author(s):  
S. A. Barwick ◽  
D. J. Brown ◽  
B. R. Cullis ◽  
A. K. Bell ◽  
T. J. May ◽  
...  
Keyword(s):  
Evaluation System ◽  
New South ◽  
New South Wales ◽  
Reproductive Rate ◽  
Multiple Births ◽  
Net Reproductive Rate ◽  
Average Performance ◽  
Genetic Base ◽  
South Wales ◽  
Selection For

Aims We examine the average performance of Border Leicester (BL) flocks that are part of LAMBPLAN, Australia’s sheep performance recording and genetic evaluation system. We also summarise outcomes from the New South Wales Department of Primary Industry’s research on BL improvement, and discuss the performance required for the BL to continue to be a pivotal part of the Australian prime lamb industry. Key results Modest gains have been recorded in the BL in growth since 2000 and faecal egg counts have reduced, suggesting improved worm resistance. The net reproductive rate has slightly improved, while inbreeding continues to increase. In work conducted by the New South Wales Department of Primary Industries, an improved BL flock, encompassing selection for multiple births and a broadening of the breed’s genetic base, had advantages over purebred BLs in many aspects of performance, including a 19.3% advantage in the net reproductive rate. Advantages in fertility were ~5%, litter size ~7% and lamb rearing ability ~5%. BL improved × Merino and (BL improved × BL) × Merino crossbred ewes also had advantages over traditional BL × Merino ewes in their joining performance when joined to Dorset rams. Conclusions Selection in the BL needs to emphasise traits in a manner consistent with their importance to commercial lamb production. Implications Embracing this selection and broadening the BL’s genetic base will assist the BL to maintain its place in the Australian lamb industry.

PUBERTAL DEVELOPMENT OF RAM LAMBS: BODY WEIGHT AND TESTICULAR SIZE MEASUREMENTS AS INDICES OF POSTPUBERTAL REPRODUCTIVE FUNCTION

1990 ◽  
Vol 70 (1) ◽  
pp. 139-147 ◽  
Author(s):  
T. A. YARNEY ◽  
L. M. SANFORD ◽  
W. M. PALMER
Keyword(s):  
Semen Quality ◽  
Pubertal Development ◽  
Reproductive Function ◽  
Reproductive Traits ◽  
Scrotal Circumference ◽  
Ejaculation Frequency ◽  
Testicular Size ◽  
Ram Lambs ◽  
Sperm Output ◽  
The Relationship

The relationship between the pattern of early testicular growth and postpubertal spermatogenic function and libido was investigated with 14 Suffolk rams born in March. Scrotal circumference and testicular diameter (TD) measurements were taken every 10 d between 30 and 190 d of age, and at 13 and 17 mo. Daily sperm output (DSO, sperm voided in urine) or semen quality, and libido were assessed at approximately 6, 13 and 17 mo of age. At 6 mo of age, rams with the larger testes had a greater DSO (r ≥ 0.77, P < 0.01) and mated estrual ewes more frequently (r ≥ 0.72, P < 0.01). Rams with larger testes at 13 mo had a greater DSO (r ≥ 0.74, P < 0.01), and those with larger testes at 17 mo ejaculated a higher percentage of motile spermatozoa (r ≥ 0.55, P < 0.05) and a greater number of spermatozoa (r = 0.61, P < 0.05; TD only). DSO at 13 mo was related to testicular size (r ≥ 0.54, P < 0.05) between 150 and 190 d of age. There were also correlations between the number of spermatozoa ejaculated at 17 mo and testicular size measurements (r ≥ 0.56, P < 0.05) taken between 170 and 190 d. However, ejaculation frequency (EF) at both 13 and 17 mo was not related to earlier testicular size measurements. Whereas testicular size and spermatogenic function of yearling Suffolk rams relate to testicular size measurements taken at about 6 mo of age, juvenile testicular size measurements correlate with EF only in the immediate postpubertal period. Key words: Sexual maturation, reproductive traits, interrelationships, ram

Sign in / Sign up

Export Citation Format

Share Document