13 results
The effect of three different growth rates on some offal components of cattle
- D. M. Murray, N. M. Tulloh, W. H. Winter
-
- Journal:
- The Journal of Agricultural Science / Volume 89 / Issue 1 / August 1977
- Published online by Cambridge University Press:
- 27 March 2009, pp. 119-128
-
- Article
- Export citation
-
This paper describes the effect of three different growth rates on some offal components of Angus cattle. The growth rates were: high (H, 0·8 kg/day), low (L, 0·4 kg/day) and high-maintenance (HM, 0·8 kg/day followed by a period during which body weight was held constant).
Equations are presented which enable the weights of the offal components to be calculated within the body weight range 300–440 kg.
For most tissues, weights in the H group were greater than in the L and HM groups and included: liver, rumen-reticulum, small intestine and the total alimentary tract. Weight of fat trimmed from the rumen-reticulum, omasum, large intestine and total alimentary tract was also greater in the H than in the L and HM groups. The reverse situation held for head, feet and tail and the spleen.
In spite of these differences between groups in weights and composition of offals, the carcass composition in all groups was similar (Murray, Tulloh & Winter, 1974). It appears that, at a given body weight, changes in the offals may buffer the carcass against change in composition when cattle are exposed to different growth patterns.
Effects of two paths of live-weight change on the efficiency of feed use and on body composition of Angus steers
- Janet Z. Foot, N. M. Tulloh
-
- Journal:
- The Journal of Agricultural Science / Volume 88 / Issue 1 / February 1977
- Published online by Cambridge University Press:
- 27 March 2009, pp. 135-142
-
- Article
- Export citation
-
This paper describes the effect of two paths of weight change on the total feed consumed and on body composition at slaughter of Angus steers. The treatments were: a 15% weight loss from 330 kg live weight, at 0·5 kg/day for 100 days, followed by recovery to 330 kg on ad libitum feed intake (WL/WG group), and constant weight at 330 kg for the same length of time as corresponding paired animals in the WL/WG group took to complete their treatment (constant-weight group). There were six animals in each group and they were slaughtered when the WL/WG steers reached 330 kg. At the beginning of the experiment four animals (preliminary group) were slaughtered at 330 kg.
Intakes of feed were recorded and measurements of apparent dry-matter digestibility were made at intervals. Chemical analyses were carried out on the right side of each carcass and on the other components of the body.
The mean total intake of the WL/WG group was 12% less than that of the constant-weight group. The daily dry-matter intake in the constant weight group decreased from 5·9 kg to 4·4 kg during the experiment.
The time taken for the WL/WG steers to regain the 50 kg weight loss varied from 30 to 68 days. Their intakes at this time and their growth rates were similar to those that they experienced when they grew to 330 kg for the first time.
Apparent digestibility varied between animals but was not influenced by treatment. The constant-weight group were fatter than the WL/WG group at slaughter and had heavier carcasses, both differences being significant (P < 0·05). The difference between groups in empty body weight was not significant. Animals from the final slaughter groups had significantly heavier heads and feet and a higher ash content than the younger steers of the preliminary group. Liver weights were reduced by nutritional restriction and did not fully recover in WL/WG steers.
Effects of a severe nutritional check in early post-natal life on the subsequent growth of sheep to the age of 12–14 months: Changes in body weight, wool and skeletal growth, and effects at the cellular level
- D. L. Hopkins, N. M. Tulloh
-
- Journal:
- The Journal of Agricultural Science / Volume 105 / Issue 3 / December 1985
- Published online by Cambridge University Press:
- 27 March 2009, pp. 551-562
-
- Article
- Export citation
-
The growth of 26 castrated ram lambs was severely restricted for the first 5 weeks of post-natal life. Subsequently, these lambs (group R) were fed ad libitum on the same high quality diets as fed to a control group of 26 similar lambs (group C) from birth.
At regular intervals lambs were weighed, X-rayed and surface measurements were aken. At the age of 12–14 months, covering the body-weight range of 63–83 kg, ten animals from each group were slaughtered for dissection and measurement. These data were used to compare the skeletal growth of the two groups of animals. Measurements of skeletal dimensions by dissection were compared with measurements obtained by surface and radiographic techniques. After slaughter, the brain, kidneys, liver, the left semitendinosus and gastrocnemius muscles from each lamb were used for the following analyses: dry matter, ash, fat, protein, DNA and RNA contents.
At the end of the period of feed restriction, there was a mean body-weight difference between groups of 9·2 kg (63%).This represented a weight for age difference of 36 days, which was reduced to 29 days at the conclusion of the experiment, restricted animals not having fully recovered from the period of underfeeding.
Clean wool production per day was significantly (P < 0·05) depressed by the restricted feeding, lambs in group C producing 11·07 g/day during the first shearing interval compared with 10·07 g/day from group R lambs. There was no difference between groups in clean wool produced during the second shearing interval.
Restricted feeding caused a reduction in the rate of bone growth but, during subsequent regrowth (apart from minor exceptions), it did not disrupt the relationship of skeletal dimensions to fleece-free body weight (FFBW). Surface measurements showed that during recovery, group R animals were significantly narrower (P < 0·05) at the hips and wider (P < 0·05) at the shoulders than group C animals. The results obtained from the radiographs for length of foreleg were similar to those obtained from surface measurements. Metacarpal width (measured at two sites) and weight were significantly greater in group R than in group C animals. With the exception of width at hips and although not statistically significant (P > 0·05), the skeletal measurements of group R were slightly greater than those of group C animals. This may have been due to the slightly greater age of group R at slaughter and to an effect of restricted feeding.
There was no significant difference between groups R and C in the DNA content of the tissues investigated. Neither was there any difference between the groups in cell size as indicated by the protein: DNA and tissue weight: DNA ratios. Even though hyperplasia and hypertrophy were slowed by the period of restricted feeding, this effect was transient, full recovery apparently occurring as indicated by tissue weights and composition at the time of slaughter. The RNA and the protein contents of the tissues were similar in both groups. In addition, the similarity of the RNA:DNA ratios suggests that tissues in each group possessed the same capacity to synthesize protein.
In practical terms, the recovery of group R was associated with a time lag in reaching any particular body weight and a loss of wool production. Both of these consequences are of economic importance. At the time the experiment ended, no skeletal stunting was evident in these sheep and, apparently, they had recovered in terms of cellular growth.
The effect of compensatory growth in sheep on empty body weight, carcass weight and the weights of some offals
- W. H. Winter, N. M. Tulloh, D. M. Murray
-
- Journal:
- The Journal of Agricultural Science / Volume 87 / Issue 2 / October 1976
- Published online by Cambridge University Press:
- 27 March 2009, pp. 433-441
-
- Article
- Export citation
-
The effects on the body composition of Corriedale wethers of weight loss, compensatory gain and constant body weight are described. Three groups of sheep were grown from 35–63 kg by different paths. The first grew continuously (fed ad libitum). The second and third groups lost 20% and 28% of body weight (restricted intake), respectively, from 48 kg and were then fed ad libitum until they reached 63 kg. Pairs of animals were slaughtered at intervals in each group. A fourth group of sheep was maintained at 48 kg. Analyses of covariance comparing regression equations were used to determine differences in body composition between the first three groups.
The compensatory growth rates of both groups which had lost weight were 1·5–2 times those during continuous growth. These increases were associated with an increased gut content of these animals and a concomitant reduction in the proportion of empty body weight (EBW) and carcass weight (CW) in t he full body weight (FBW). Thus, the apparent dressing percentage (CW/FBW x 100) was reduced by 2% during compensatory growth. The carcass length was not reduced during weight loss and its growth in relation to the CW was not affected by treatment. Thus compensatory growth animals had longer carcasses. Similar increases in gut contents and carcass length were found for animals maintained at constant body weight.
During developmental growth the proportions of the external offals, organs and gut tissue decreased in relation to the EBW; notable exceptions were the large intestine and caul fat where the proportions remained constant and increased, respectively.
The growth of the CW, lungs, large intestine and head were not reversed during weight loss whilst the liver, heart, hide and gut tissues (except the large intestine) all lost more weight during weight loss than they had gained during the growth phase. The proportions of these latter components were increased in relation to the EBW during the ensuing compensatory growth.
In general, the composition of animals held at constant body weight was similar to that of animals experiencing compensatory growth at the same weight and age.
The effect of severe nutritional deprivation in early post-natal life on tissue and cellular responses during subsequent growth of lambs to the age of 4 months
- N. M. Tulloh, Helen Brimblecombe, Carolyn Dennis
-
- Journal:
- The Journal of Agricultural Science / Volume 106 / Issue 2 / April 1986
- Published online by Cambridge University Press:
- 27 March 2009, pp. 341-350
-
- Article
- Export citation
-
The growth of 16 ram lambs was severely restricted for the first 6 weeks of post-natal life. Subsequently, these lambs (group R) were fed ad libitum. The diet was based on reconstituted cows' whole milk and lucerne chaff. A control (group C) of 16 similar lambs was fed ad libitum on the same diet from birth.
Lambs were weighed regularly and, in group C, four lambs were killed at the age of 1 day and then two at each of the following body weights: 10, 15, 20, 25, 30, 35 kg. In group R, five lambs were killed at the commencement of ad libitum feeding (age 43 days) and two each at the same body weights as in group C, except that only one lamb was available at 20 kg. After slaughter, the brain, liver, kidneys and the semitendinosus and gastrocnemius muscles were removed, weighed, stored and, with the exception of the liver, were analysed later for the following components: DNA, RNA and protein. Carcass weight and the weight of the kidney and channel (KC) fat were recorded. The femurs and metacarpals were removed from each carcass and cleaned, weighed and measured.
During the 6 weeks of restricted feeding, group R gained 0·9 kg while the ad libitum group C gained 13·5 kg. However, during recovery, group R grew faster than group C (0·37 ν 0·34 kg/day), reducing the weight for age difference near the end to 29 days at mean body weights of 30 kg.
Because of the design of the experiment, at the same age all measurements on group R animals, after the commencement of ad libitum feeding, were smaller than in group C. For this reason, the interpretation of the results has been based on differences between regression equations relating the various measurements to empty-body weight or to one another.
At the start of ad libitum feeding, brain weight, carcass weight, femur weight and femur length were bigger, while liver weight and KC fat weight were smaller in group R than in group C. At the end of the experiment, there were no significant differences between treatments for these measurements. Metacarpal shape differed between groups, the bone being relatively longer and narrower in group R than in group C, throughout the period of ad libitum feeding.
There were no significant differences between treatments in the relationships between DNA and corresponding tissue weights. However, the RNA was significantly less in both muscles in group R than in group C at the beginning of ad libitum feeding, but this difference had disappeared by the end of the experiment.
The brain protein: DNA and the brain weight: DNA ratios did not differ between treatments nor did they change significantly during the experiment. The semitendinosus was the only other tissue for which protein content was available and the protein: DNA ratio for this muscle differed between treatments, reflecting an acceleration of division by cell nuclei during the recovery period. The other tissue weight: DNA relationships did not differ between treatments and all ratios increased to values similar to those reported elsewhere. RNA:DNA ratios differed between treatments for both muscles, suggesting that high rates of protein synthesis occurred in group R during the recovery period.
In spite of the apparent normality of group R when measurements were related to EBW or tissue weights at the end of the experiment, only a long-term investigation would determine whether the weight-for-age difference of the type reported here would persist in adult life.
A comparison of body composition and tissue distribution of Friesian and Angus steers
- T. G. Truscott, C. P. Lang, N. M. Tulloh
-
- Journal:
- The Journal of Agricultural Science / Volume 87 / Issue 1 / August 1976
- Published online by Cambridge University Press:
- 27 March 2009, pp. 1-14
-
- Article
- Export citation
-
Fourteen Friesian and 13 Angus steers, grown at pasture, were selected so that their carcass weights fell evenly throughout the range 200–300 kg. The right half of each carcass was dissected into muscle, fat, bone and fascia and tendon, and the left half boned-out and fat trimmed into retail cuts. A step-wise multiple regression procedure, including a pseudovariable for breeds, was used to compare compositional components on a common weight basis.
Angus, at the lower end of the live-weight range, had heavier empty bodies than Friesians; at the heavier end of the live-weight range, this was reversed. This relationship between live weight and empty body weight was due to variation between breeds in the weight of contents in the fore stomachs but not the intestines.
When compared at either the same live weight or the same empty body weight, Angus had more hot carcass than the Friesians (8·0 and 8·4 kg, respectively). There was no difference between breeds in loss of carcass weight in the 24 h post-slaughter.
There was no breed difference in weight of blood, head, kidney and channel fat, kidneys, liver, diaphragm, heart, lungs, tail or fore-stomachs, when compared at the same offal weight. The feet and intestines were, respectively, 0·55 and 2·43 kg heavier for Friesians than for Angus at the same offal weight, but the pizzle was 0·11 kg lighter. Hide weight was greater in the Angus at all offal weights, with the difference between breeds being 0·016% of (offal weight).
There was no difference between breeds in the weight of muscle or the weight of fascia and tendon when compared at the same dissected side weight; however, the Angus had 4·8 kg more fat and 3·0 kg less bone than the Friesians at the same dissected side weight.
When compared at the same muscle weight the Friesians had 1·04 kg more proximal hind-limb muscles, 0·30 kg more proximal fore limb muscles, but 0·74 kg less abdominal muscles than the Angus. At all dissected muscle weights the Angus had a greater weight of muscles of the neck and thorax, and this difference increased with increasing weight of dissected muscle. The Friesians also had 1·52% more of their muscle as ‘expensive muscle’. There were no breed differences in the distribution of any other muscle groups.
There was no breed difference in the distribution of dissected fat between subcutaneous and intermuscular depots when these were the only fat depots considered. However, when kidney and channel fat was included in the total dissectable fat of the carcass, Friesians had 22·4 % more kidney and channel fat, the same weight of intermuscular fat and less subcutaneous fat than the Angus at the same total dissected fat weight.
Friesians tended to have more of their bone weight in their legs (humerus, femur, tibiar–tarsus, radius–ulnar–carpus) and Angus more in their thoracic region (thoracic vertebrae and ribs, scapular and sternum-costal cartilages).
At the same retail side weights there was no difference between breeds in the weight of fat-trimmed, boned-out, retail cuts; however, the Friesians had 3·3 kg more retail bone than Angus, but 2·3 kg less fat trim and 0·46 kg less sausage mince.
There was no difference between breeds in the distribution of retail bone or of fattrimmed, boned-out cuts between the forequarter and hindquarter. However, the Friesians had 13·2 % more fat trim in the hindquarter. Friesians had 0·27 kg more retail cuts located in the rump but 0·80 kg less in the loin, when compared at the same weight of retail cuts. Also, the Friesians had more of their retail cuts as topside, thick flank and foreshin. There were no other differences between breeds in the distribution of retail cuts.
Effects of three different growth rates on empty body weight, carcass weight and dissected carcass composition of cattle
- D. M. Murray, N. M. Tulloh, W. H. Winter
-
- Journal:
- The Journal of Agricultural Science / Volume 82 / Issue 3 / June 1974
- Published online by Cambridge University Press:
- 27 March 2009, pp. 535-547
-
- Article
- Export citation
-
A study was made of the effect on body composition of growing Angus steers from 300 to 440 kg at three different rates. The rates were: High (H) 0·8 kg/day, Low (L) 0·4 kg/day and High-Maintenance (HM) 0·8 kg/day followed by a period during which body weight was maintained constant.
The animals were individually penned and the different growth rates were achieved by controlling intakes of a pelleted feed. Two animals (part of H treatment) were killed at 300 kg and the remaining 27 animals (nine in each treatment), were killed at common body weights of 330, 363, 400 and 440 kg.
Analyses of covariance were used to compare linear regression equations representing results from each treatment. In order to do this, the logarithmic transformation of the allometric equation, y = axb, was used. As a proportion of empty body weight (EBW), hot carcass weight (HCW) was greater in both the HM and L groups than in the H group, indicating a greater offal component of EBW in the H animals. The loss in weight of the dressed carcass during storage at 2 °C for 24 h was similar in all three groups and was 0·98% of HCW. The proportions of HCW in the fore- and hind-quarters were similar in each group.
At the same dissected side weight (DSW), the weight of bone was significantly greater in both the HM and L groups than in the H group indicating that bone development was related to both age and carcass weight. There were no significant differences between the groups in the proportions of either muscle or total fat. However, the proportion of kidney and channel fat in the H group was greater than in the HM and L groups and the proportion of subcutaneous fat was also greater in the H than in the L group. The amount of connective tissue in the three groups followed, in general, group differences in bone. Analyses of the dissected components of the separate fore- and hind-quarters showed that the difference between the H and L groups in the proportion of subcutaneous fat in the DSW was due to a relatively greater development of this fat in the fore-quarter of the H animals.
No differences were found between treatments in the proportion of ‘expensive muscles’ relative to total side muscle (TSM). However, there were treatment effects on the proportions of TSM formed by certain groups of muscles; two examples are: the proportion of group 4 muscles (abdominal muscles) was higher and the proportion of group 6 muscles (distal muscles of the fore-leg) was lower in the H than in the L treatments. Bone weight distribution was similar in all treatments.
There were differences between the H and HM groups in the relative growth ratios for all fat tissues (subcutaneous, intermuscular and kidney and channel fat) compared with total side fat. However, in the H and L groups, the relative growth ratios for corresponding fat categories were similar. The weight of kidney and channel fat in the left side of the carcass was significantly greater than in the right side of the carcass in all treatments.
The effect of three different growth rates on the chemical composition of the dressed carcass of cattle and the relationships between chemical and dissected components
- D. M. Murray, N. M. Tulloh, W. H. Winter
-
- Journal:
- The Journal of Agricultural Science / Volume 85 / Issue 2 / October 1975
- Published online by Cambridge University Press:
- 27 March 2009, pp. 309-314
-
- Article
- Export citation
-
This paper describes the chemical composition of dressed carcasses of Angus steers and relationships between chemical and dissected components of these carcasses. These cattle were grown from 300 to 440 kg at three different rates. The rates were: High (H, 0·8 kg/day), Low (L, 0·4 kg/day) and High-Maintenance (HM, 0·8 kg/day followed by a period during which body weight was maintained constant).
There were no significant differences between treatments in the regression equations for weight of water, protein or chemical fat against left side weight (half carcass). However, weight of ash was significantly greater in the HM group than in the H group. These results are similar to those obtained with dissection data on the right side of the same carcasses.
There were no significant differences between treatments for regression equations predicting dissected composition from chemical composition. The common regressions for each component are as follows:
log y (total side muscle) = 0·282 + 1·061 log × (protein) (Sν,× 3%), (i)
log y (total side bone) = 1·055 + 0·836 log × (ash) (Sν×) (ii)
log y (total side fat) = – 0·380 + 1·076 log × (chemical fat) (Sν,× 4%), (iii)
where all values of × and y are in grams.
Equations (i) and (ii) were used to predict the dissected composition of Angus steers from another experiment in which one group of cattle lost weight. Equation (i) gave useful predictions but equation (ii) did not.
Growth patterns in sheep: the effects of weight losses on compensatory growth and feed intake in Corriedale sheep
- B. V. Butler-Hogg, N. M. Tulloh
-
- Journal:
- The Journal of Agricultural Science / Volume 99 / Issue 3 / December 1982
- Published online by Cambridge University Press:
- 27 March 2009, pp. 641-649
-
- Article
- Export citation
-
The growth and feed intakes of Corriedale wether sheep when grown from 30 to 50 kg body weight by five different growth paths are described.
Group A (control) grew continuously (fed ad libitum). After reaching ca; 40 kg body weight, group B and C animals lost 21% of their initial body weight over 9 and 18 weeks and at 122 and 63 g/day, respectively, and began realimentation at 30 kg body weight. Group D and E animals were ca. 50 kg body weight when weight loss was imposed and they lost body weight at similar rates (125 and 157 g/day) respectively. Animals in group D lost 34% of their initial body weight over 18 weeks and began realimentation at 30 kg body weight (the same as groups B and C). Group E animals lost 23% of their initial body weight over 9 weeks to begin realimentation at 35 kg body weight. Except during periods of weight loss, animals were fed ad libitum. Compensatory growth was observed in all groups which had lost weight, with early recovery growth rates 1·6–1·8 times higher than control sheep of the same weight.
Rate of body-weight loss did not induce any significant differences in response to realimentation but results (groups B and C) suggest that the more rapid the loss, the more rapid will recovery be during realimentation. When sheep at different body weights lost the same proportion of their initial body weights, the heavier sheep (group E) attained final slaughter weight quicker than the lighter sheep (group B). When the proportion of body weight lost to reach a particular lower body weight was varied (groups B and D), the greater weight loss was associated with higher and more persistent growth rates during realimentation.
After weight loss, ad libitum dry-matter intake was significantly lower during the first 10 kg of gain during realimentation in all treatment groups (B, C, D, E) than in control group A. There were no differences between treatment groups in recovery of dry-matter intake.
Gross efficiency in all treatment groups was higher than in the control group A during the first 10 kg of recovery of body weight, but it then declined rapidly. This increase in gross efficiency was considered to be due to a combination of increased growth rates, reduced feed intakes and lower maintenance requirements. When the complete growth paths from 30 to 50 kg were considered, there were no significant differences in total feed consumed by the sheep following the five different growth paths.
Effects of weight loss in ewes in early pregnancy on muscles and meat quality of lambs
- D. I. KRAUSGRILL, N. M. TULLOH, W. R. SHORTHOSE, K. SHARPE
-
- Journal:
- The Journal of Agricultural Science / Volume 132 / Issue 1 / February 1999
- Published online by Cambridge University Press:
- 01 February 1999, pp. 103-116
-
- Article
- Export citation
-
Three successive experiments, of similar design, were carried out during 1986–88 at Mount Derrimut, Australia. Mature Merino ewes were mated to Poll Dorset rams and then allocated to either a control group (C) or a treatment group (R). Ewes from each treatment were slaughtered 60, 70, 100 or 140 days post-conception and the development of their foetuses was compared in terms of body size and muscle characteristics. In Expts 1 and 2, some ewes were allowed to lamb and the progeny in each group were slaughtered after reaching a body weight of 35 kg, for comparison of growth rates, muscle characteristics and meat quality.
In each experiment, treatment extended from mating to day 70 of pregnancy and, during this period, both groups were housed. Ewes in group C were kept as one group and fed ad libitum and ewes in group R were individually penned and fed a restricted ration of the same diet as that given to group C in order to achieve a steady loss of body weight. In Expt 1, this loss was 8 kg but, in Expts 2 and 3, feed intake was controlled according to condition score and, during this period, group R ewes lost 25–35% of their body weight at mating. After day 70, all ewes were kept grazing and were offered supplementary feed at rates sufficient for a steady increase in ewe body weights.
Foetuses in group R were lower in body weight (P<0·05), crown-rump length (P<0·05) and girth (P<0·01). However, birth weights and mean ages of the 35 kg lambs at slaughter did not differ significantly between treatments.
There were no significant differences between treatments for the semitendinosus (ST) and semimembranosus (SM) muscles in total muscle weight, DNA content, protein content, nor in the ratios of muscle weight[ratio ]DNA and protein[ratio ]DNA. However, there were significant differences between experiments, which indicated that cell size in the ST and SM muscles was lower in Expt 2 than in Expt 1.
In day 70 foetuses, the cross-sectional area of α fibres was greater (P<0·05) in group R than in group C but by day 140 the difference was no longer significant. At day 70, there was also a positive correlation (r=0·65, P<0·01) between the cross-sectional area of β fibres and the number of α fibres surrounding each of them. There were no significant differences between treatments at any age in the percentages of βR, αR and αW fibres.
Meat from group R lambs was more tender than that from group C lambs as indicated by significantly lower means in the SM muscle for adhesion (P<0·01) and Warner–Bratzler Peak Force (WB PF) measurements (P<0·05).
Although some effects of nutritional restriction were found, severe feed shortage in early pregnancy in sheep is unlikely to have significant effects on the production of prime lamb meat provided that adequate nutrition is available during late pregnancy and post-natal growth.
Growth of sheep to the age of three years after a severe nutritional check in early post-natal life
- D. I. KRAUSGRILL, N. M. TULLOH, D. L. HOPKINS
-
- Journal:
- The Journal of Agricultural Science / Volume 128 / Issue 4 / June 1997
- Published online by Cambridge University Press:
- 01 June 1997, pp. 479-494
-
- Article
- Export citation
-
At Mount Derrimut Field Station from 1982 to 1985, growth and body composition was studied in three groups of wethers from the same flock. A control group (C) and a restricted group (R) were housed from the age of 1 day until slaughtered. The first slaughter was at the age of c. 1 year (reported elsewhere) and the second at the age of c. 3 years. Apart from the first 36 days, when group R was fed a severely restricted ration, both groups were fed a high quality diet ad libitum throughout the experiment. At the end of the second year, a group of 2-year-old wethers (G) was introduced, to compare the growth of these sheep with those in groups C and R. Group G sheep were reared on their dams, kept as grazing animals and killed at the second slaughter.
At the age of c. 3 years there was no significant difference between groups C and R for mean fleece-free body weights, but the sheep in group G were significantly lighter (P<0·01) in spite of reaching mature size for grazing sheep in the general flock.
After the age of 7 months there was no significant difference between groups C and R in rate of wool production. Rate of wool production in group G sheep was not significantly different from that of sheep in the other groups except during the last 6 months, when they produced significantly less wool (P<0·05).
Regression analyses for surface and X-ray measurements against fleece-free body weight (independent variable) showed no differences between groups C and R, except for width of metacarpal (X-ray measurement). In this case, the regression coefficients were different (P<0·01) but, at slaughter, actual bone measurements were the same. Both X-ray measurements and those at dissection showed that the metacarpals of group G were significantly (P<0·05) longer and narrower, and had a narrower cortex, than those in the other two groups (P<0·05).
There were no significant differences between groups C and R in mean weight and chemical composition of the parts and tissues examined; however, the carcass fat content of sheep in group G was significantly less (P<0·01) than in the other two groups. The sheep in group G had higher weights (P<0·01) for the brain, the digestive tract (DT), kidneys and liver than those in groups C and R.
Cell size in the semitendinosus muscle, as indicated by the protein[ratio ]DNA ratio, increased (P<0·01) between the first and second slaughters. There were no differences between groups in protein[ratio ]DNA ratios, but the DNA and protein contents were significantly higher (P<0·05) in the kidneys and liver in group G than in the other groups. Although the weights of the semitendinosus muscle were heavier (P<0·01) in groups C and R than in group G, on a fat-free basis, there were no significant differences between treatments in muscle weight or in DNA and protein contents.
It is concluded that sheep will make a complete recovery after a severe nutritional check in early post-natal life if given the opportunity to do so. Even though large differences in body weight may develop between sheep, this appears to have little effect on mature skeletal dimensions. However, at maturity, with grazing sheep that grow relatively slowly, the metacarpals are likely to be narrower and longer than those of the same genotype fed to grow faster. Even with sheep fed ad libitum throughout life, the use of X-ray and surface measurements in young sheep at a particular body weight are unlikely to be useful for the accurate prediction of mature body weight.
A seriatim study, using ultrasonic measurements, of fat depth and m. longissimus area in Hereford bulls, steers and heifers under grazing conditions
- T. G. Truscott, N. M. Tulloh, D. E. Whitfield
-
- Journal:
- Animal Production / Volume 30 / Issue 2 / April 1980
- Published online by Cambridge University Press:
- 02 September 2010, pp. 199-209
- Print publication:
- April 1980
-
- Article
- Export citation
-
Measurements of live weight and of ultrasonic (Scanogram) fat depth and m. longissimus cross-sectional area at the 12th/13th rib were taken at 4— to 6-week intervals from 10 to 35 months of age (23 occasions) on 15 Hereford males (bulls), 15 castrate males (steers) and 15 females (heifers) managed under grazing conditions.
Mean rates of live-weight change throughout the measurement period (0·51, 0·47 and 0·39 kg/day for bulls, steers and heifers, respectively) were significantly different. When compared at the same ages, fat depth was similar in the steers and heifers, beginning at about 3 mm and increasing to 11 mm. Fat depth changed little in the bulls, beginning at 1·7 mm and increasing to 3 mm. At the same age, bulls had larger m. longissimus cross-sectional areas than steers and steers had larger muscle cross-sectional areas than heifers.
Absolute variation within sex groups increased throughout the experiment in live weight and fat depth, but not in m. longissimus crosssectional area. Simple correlation coefficients, pooled within sex groups, of relationships between the same measurements at various measuring occasions, indicated that measurements of fat depth and of muscle cross-sectional area at 10 to 12 months of age are poor indicators of these measurements at periods of 6 months or more later in life.
When compared at the same live weights, heifers had the greatest and bulls had the smallest fat depth and, within animals, fat depth was closely related to live weight. At any live weight, m. longissimus cross-sectional area was less in heifers than in steers and bulls, which were not significantly different from each other in this trait. Equations relating fat depth and muscle area to live weight are presented and, under the conditions of this study, indicate that there is no basis for adjustment of fat depth for live weight in bulls subjected to contemporaneous selection.
The representation of yield of dressed carcass
- R. M. Seebeck, N. M. Tulloh
-
- Journal:
- Animal Production / Volume 8 / Issue 2 / June 1966
- Published online by Cambridge University Press:
- 02 September 2010, pp. 281-288
- Print publication:
- June 1966
-
- Article
- Export citation
-
1. Because dressing percentage increases as body weight increases, an adjustment for body weight is necessary when the dressing percentages of animals of different body weights are being compared. Instead of comparing animals on this basis, it is suggested that the power function y = axb, relating carcass weight and body weight, when computed in the logarithmic form, provides a suitable method for making adjustments of this kind.
2. Using this function, differences in yield of carcass have been shown, between breeds and between seasons, in a study involving Hereford, Aberdeen Angus and Beef Shorthorn cattle.
3. A similar function has been used to describe the relationship between fat content of carcass and carcass weight and body weight, using data from the same breed study.