Cannon Bone Length Research Articles

Intermandibular width and and cannon bone length in “winners” versus “others”

Summary Conformation is defined as the form or outline of an animal and is sometimes expanded to include a relationship of form to function. In the course ofa studentproject,25 traits were measured in each of 20 Thoroughbreds as 3-year-olds in training. Winners were three year olds who had won a listed race in 1990 as two year olds. Others were three year olds who had raced but not won in listed races in 1990 as two year olds. Twelve of these Waits were evaluated using a linear assessment scoring system; 13 traits were measured using a steel tape, vernier calipers or an improvised compass. This short communication confines itself to two measured waits, intermandibular width and cannon bone length.

Genetic and environmental effects on carcass characteristics of Southdown × Romney lambs: II. Genetic and phenotypic variation

Approximately 4,400 crossbred lambs from Southdown sires and Romney ewes were slaughtered at approximately 18, 23, and 28 wk of age over a 16-yr period. Live weights, carcass measurements, and chemical percentages were analyzed to estimate genetic and phenotypic parameters. Heritabilities of postweaning weights and gains were about .20. Heritabilities of fat and water percentages were about .35 adjusted for age. Heritability of kidney fat percentage was .53. Heritabilities of fat depth and muscle measurements ranged from .21 to .37. Crutch depth (h2 = .73) and cannon bone length (h2 = .74) were the most highly heritable carcass measurements. The genetic correlation between carcass fat and fat-free weight was .47 when lambs were slaughtered at a constant age. Fat-free weight was nearly uncorrelated with percentages of fat, water, and protein when lambs were slaughtered at the same age. Carcass measurements increased accuracy of selection for fat-free weight at a constant age very little compared with using only carcass weight. However, this does not mean that additional measurements are useless. The addition of carcass measurements to the selection criteria would result in correlated responses in chemical composition that more closely resembled direct selection for fat-free weight. Carcass weight would be of little value when used by itself to reduce fat weight adjusted for carcass weight. Direct measurement of carcass composition resulted in 1.6 to 2.6 times more predicted response for reduced fat weight than any combination of carcass weight and one fat depth measurement.

Body measurements of crossbred calves sired by Simmental bulls divergently selected for progeny first-calf calving ease in relation to birth weight.

Simmental bulls (n = 27) were divergently selected on linear model first-calf calving ease expected progeny difference (CEPD) relative to birth weight expected progeny difference (BEPD) so that body measures of calves from sires whose progeny tended to be born either with more or less dystocia than expected from BEPD could be obtained. At birth, calf weight, head circumference, shoulder width, hip width, heart girth, cannon bone circumference and length, and body length were recorded for 204 calves. These measures had also been obtained from the Polled Hereford X Angus dams of the calves at their births. Sire differences (P less than .05) existed for calf cannon bone circumference and length before and after adjustment for gestation length and birth weight of the calf. Sire BEPD was positively associated with cannon and head circumferences independent of phenotypic birth weight and gestation length. No relationship existed between CEPD or threshold model first-calf calving ease expected progeny difference and any calf measure, either before or after adjustment for birth weight. Multivariate factor analysis was used to describe independent components of skeletal width, frame, and thickness after removal of birth weight effects; factors were not related to genetic merit for calving ease or observed calving performance. Independent of weight, newborn calf measures were not highly related to body measures at weaning or to dam birth measures. Body shape differences at constant weight existed in crossbred calves, but they were not related to sire genetic merit for calving ease or measured dystocia. Selection for calf body shape, independent of birth weight, would not reduce dystocia.

Body measurements of newborn calves and relationship of calf shape to sire breeding values for birth weight and calving ease.

Body measurements on Angus- (n = 374) and Polled Hereford-sired (n = 438) calves were used to quantify calf shape via multivariate factor analysis, and measurements on Polled Hereford-sired calves were further used to investigate relationships between calf shape and sire expected progeny differences (EPD) for birth weight and first-calf calving ease. Calf birth weight, head circumference, shoulder width, hip width, heart girth, cannon bone circumference and length, and body length were recorded at 24 h postpartum. Sire birth weight EPD was positively associated (P less than .05) with all calf measures but only with head and cannon circumference after adjustment for phenotypic birth weight and gestation length. Thus, at constant birth weight, calves from higher birth weight EPD bulls tended to have larger cannon and head circumferences. Calving ease EPD was negatively related (P less than .05) to all calf measures except shoulder width. After adjustment for birth weight, only cannon circumference was associated with calving ease EPD, and this effect was removed by additional adjustment for birth weight EPD. Thus, at constant birth weight, bulls with higher EPD for calving ease sired calves with smaller cannon circumference, but at constant birth weight EPD, body measures were not associated with calving ease EPD. Factor analysis defined underlying skeletal width and frame components of shape (independent of birth weight) for both sire breeds. Calf shape differed among sires and was in part explained by birth weight EPD. No additional variation in shape was explained by calving ease EPD. Calf shape seemed to add no information for prediction of dystocia to that provided by birth weight EPD.

Predicted and realized responses to selection for an index of bone length and body weight in Scottish Blackface sheep 2. Correlated responses in lifetime productivity

ABSTRACTA selection experiment with Scottish Blackface sheep was used to compare predicted and realized correlated responses to selection. Three lines were maintained between 1956 and 1974 in which selection was either at random or for high and low values of an index of cannon-bone length at 8 weeks of age adjusted for body weight at the same age.There was no evidence of asymmetrical responses in any trait. Selection for increased cannon-bone length, adjusted for body weight, resulted in (i) increased body weights at all ages between birth and maturity, (ii) increased reproduction rate, principally from increased litter size but also from small responses in ewe fertility and lamb survival and (iii) decreased survival of adult ewes. The realized genetic correlations were relatively small (up to 0·3) but mostly significantly different from zero, whereas base population genetic correlation estimates were very imprecise. The realized responses in reproduction rate were probably a consequence of the genetic response in body weight.

Predicted and realized responses to selection for an index of bone length and body weight in Scottish Blackface sheep 1. Responses in the index and component traits

ABSTRACTA selection experiment with Scottish Blackface sheep was used to compare predicted and realized responses to selection. Three closed lines, of approximate annual size of 270 ewes and 10 rams, were maintained between 1956 and 1974, in which selection was at random, or for high and low values of an index of cannon-bone length at 8 weeks of age adjusted for body weight at the same age. An unselected base flock (1954-55) and the randomly selected line were used to estimate base population parameters, while the selected lines were used to estimate realized responses to selection.Heritabilities and genetic correlations were obtained in the unselected lines from a variety of collateral and ancestral relationships. The important components of phenotypic variance were estimated and likely responses to selection predicted for the index and its two component traits. Realized responses to selection were estimated from the regression of response on selection differential. The expected variance-covariance matrix of observed responses was included in generalized least-squares estimates of these regressions.The realized heritability of the index under selection, estimated from the divergence of selected lines, was 0·52 (s.e. 0·02). After allowing for the expected reduction in heritability arising from linkage disequilibrium, this was very similar to the base population estimate of 0·56 (s.e. 0·04). The responses in the component traits of the index were also very close to those expected from base population parameters

Correlated responses in lamb mortality due to long term selection for cannon bone length and fleece medullation in sheep

ABSTRACTLamb mortality in a Scottish Blackface hill sheep flock subjected to long term selection for cannon bone length and fleece medullation score was investigated, using maximum likelihood analyses. The selection for cannon bone length and for medullation score had no significant effect on lamb mortality.

Genetic studies on carcass traits in iceland twin ram lambs II. Analysis of principal components and construction of selection indices

The relationship between 20 carcass measures in twin ram lambs at the Experimental Sheep Farm, Hestur, Iceland, was studied by means of principal components. The genetic and phenotypic correlation matrices were modified by the recently developed “bending” procedure in order to reduce certain undesirable effects of sampling errors. The results of the principal component analysis indicated that a reduced number of representative variates can be extracted to form a selection criterion without incurring any great loss in efficiency. The breeding objective is assumed to be the production of compact carcasses having a large muscle to fat ratio. The selection criterion should include measures of fatness, amount of various valuable muscles, and carcass conformation. The ratio of cannonbone circumference to cannonbone length (MC/ML) was found to be a fair measure of the desired conformation. Seven traits were selected for the construction of substitution selection indices for progeny testing of rams. A carcass quality index is proposed, formed by weighting three of the substitution indices with economic values.

SOME PRENATAL EFFECTS ON BIRTH SIZE IN LINCOLN AND SOUTHDOWN LAMBS PRODUCED BY RECIPROCAL OVUM TRANSFERS

Effects at birth due to maternal environment, breed of lamb, litter size and sex of lamb on body weight and cannon bone length and width were studied in lambs born naturally and as a result of reciprocal ova transfer between Lincoln and Southdown ewes. Maternal environment, breed of lamb and litter size had a significant effect (P < 0.01) of 0.63, 0.59 and 0.61 kg, respectively, on birth weight. Effects due to sex of lamb on birth weight were small and not significant. Southdown lambs carried by Lincoln dams were 0.80 kg (25%) heavier at birth than those carried in their natural environment, but Lincoln lambs carried by Lincoln dams were only 0.50 kg (10%) heavier at birth than those carried by Southdown dams. Breed of lamb had a highly significant effect (P < 0.001) on cannon bone length, but effects due to all other factors were small and not significant. On cannon bone width only the effect of litter size was significant (P < 0.05).

SOME MATERNAL EFFECTS ON GROWTH IN LAMBS PRODUCED BY RECIPROCAL CROSSBREEDING BETWEEN LINCOLN AND SOUTHDOWN SHEEP

Effects due to maternal environment, sex of lamb and litter size on the growth of lambs were studied in lambs produced by reciprocal crossbreeding of Lincoln and Southdown sheep. At birth, maternal environment (Lincoln vs. Southdown) had a highly significant (P < 0.001) effect on the fetal weight. The difference at birth increased slightly at 40 days (weaning) but at 150 and 190 days the difference was small and nonsignificant. The effect of maternal environment on cannon bone length, although small compared with body weight, had a significant effect (P < 0.05) extending to at least 150 days of age. The difference in cannon bone width due to maternal environment was significant (P < 0.05) at birth. However, after 90 days the difference was small and nonsignificant. Litter size had a highly significant effect (P < 0.001) on body weight, cannon bone length and cannon bone width at birth and postnatally. Birth differences due to sex of lamb were rather small in all three traits, but increased as the lambs grew older. The effects of breed of sire on body weight and cannon bone length were relatively small at birth but increased with age. Breed of sire, however, had no effect on cannon bone width at birth or postnatally but interacted significantly with breed of dam on birth and weaning weight.

The effects of the plane of nutrition in early post-natal life on the subsequent growth and development of cattle

The effect of the plane of nutrition in the first 13 weeks of post-natal life of cattle on their subsequent growth rate, body shape, and carcass composition up to 12 months of age was studied. No compensatory growth to 12 months of age was observed in calves reared to 13 weeks on low planes of nutrition. There were no significant differences between Friesian and Hereford x Friesian calves, or between males and females in empty body weight or weight gains. Treatment up to 13 weeks of age had no effect on heart girth, round, head length and width, and cannon bone length, but the remaining body measurements were reduced by low planes of nutrition during this period. Differences in carcass composition were largely a reflection of the differences in empty body weight. The carcasses of the males were heavier than those of the females and the females contained a higher proportion of fat. Carcass composition, as estimated by shin dissection, indicated that Friesian calves contained more muscle than the Hereford x Friesians, and the males more muscle than the females.

CANNON BONE AND RIBEYE MEASUREMENTS OF SHORTHORN COMPARED WITH CROSSBRED BEEF STEERS

Shorthorn, Angus, Hereford and Charolais bulls were mated to Shorthorn cows, for the production of four different groups of cattle. At approximately 22 months of age, 63 of these steers were slaughtered, following a uniform feeding period in which all groups received the same roughage and grain ration. At this age all crossbreds weighed significantly (P < 0.01) more than the Shorthorn × Shorthorn. The cannon bone weight, length, circumference and thickness of the Charolais × Shorthorn steers was larger (P < 0.01) than those for all other breeds, except Hereford × Shorthorn for circumference and thickness. The Hereford × Shorthorn were superior (P < 0.05 or < 0.01) to the Angus × Shorthorn and Shorthorn × Shorthorn for the four cannon bone measurements when compared on the basis of the observed live weight but not always when compared on the basis of covariance adjusted live weight. Ribeye area was larger (P < 0.05 or < 0.01) for the Charolais × Shorthorn than for all other breeds. Ribeye area of individual breeds and breeds treated together was not associated with cannon bone measurements, when either observed or constant live weight was used.

Heterosis in crossbred hill sheep

SUMMARY1. For ten years purebred Blackface and Swaledale ewes have been kept on a small hill grazing together with first crosses and backcrosses to the Swaledale. The total flock of about 120 ewes was mated and lambed on sown pastures where ewes with twins remained from lambing until weaning. Four new rams (two of each breed) were used each year.2. It is concluded that the Swaledales produced fewer lambs than the other ewes, but these were of greater birth weight (5 %) and cannon bone length (2 %); moreoever, they were better mothers than Blackface (4 %) when rearing singles on hill grazing but not if rearing twins on sown grass.3. Blackface sheep showed greater weights at weaning (5%), at mating (5%), and of fleece (15%) than did pure Swaledales.4. First cross sheep were equal to or slightly superior to the parental mean in birth weight, weaning weight and cannon-bone length. They exceeded the better parent in ewe weight, first fleece weight, and weight of weaned lambs.5. Backcross sheep although not always statistically distinguishable from Swaledale in cannon-bone length and fleece weight or from first cross sheep in reproductive characters tend to confirm the interpretations placed on the relations between the purebred and first cross sheep.6. Heterosis estimated as a superiority of first cross sheep over the mean of the two parental breeds varied from 0% for cannon-bone length to 9·5% for prolificacy of 4-year-old ewes.