Growth and carcass composition of lambs of two breeds and their cross grazing ryegrass and clover swards

AbstractThe effects of sward, breed type and sex on lamb growth and carcass composition were measured at two degrees of maturity in live weight. The three breed types were Scottish Blackface (no. = 60), Suffolk (no. = 59) and their reciprocal crosses (no. = 60). The lambs grazed swards of either ryegrass, clover or a mixed sward intended to contain both. The proportion of the mixed sward as clover was only 0.014. Each lamb was scanned using X-ray computed tomography to measure the weights of fat, lean and bone in the carcass at two proportions of mature body weight (0.30 and 0.45). Live weights were recorded weekly. Average daily gains (ADG) in live weight and carcass tissues were calculated for each lamb between the 0.30 and 0.45 stages of maturity.At the 0-30 stage of maturity, breed type differences in carcass composition were small; the Scottish Blackface had 0.942 as much bone as the Suffolk lambs (P < 0.001), with the cross lambs intermediate. At the 0-45 stage of maturity, Scottish Blackface lambs had less fat (0.749 times as much; P < 0.001), more lean (1.065 times as much; P < 0.001) and more bone (1.055 times as much; P < 0-001) than did Suffolk lambs. The values for crossbred lambs were intermediate but closer to those of the Suffolk. Neither sward nor its interaction with breed type had any significant effect on carcass composition at either the 0-30 or 0-45 stage of maturity. The effect of sex on carcass composition was significant at the 0-45 stage of maturity when castrated male lambs had less fat (P < 0.001) and more lean (P < 0.001) than female lambs. There were breed type by sward interactions for ADG in live weight (P < 0.05), in carcass weight (P < 0.001), and in fat (P < 0.001) and bone weights (P < 0.05). The interactions were such that Suffolk lambs had higher growth rates than Scottish Blackface lambs on clover but not on ryegrass or the mixed sward. There were no significant differences between Suffolk and crossbred lambs in growth rates on any sward. In this, and in two other experiments, the extent to which growth rate declined as the nutritional environment became worse was greater (P < 0.05) in Suffolk than in Scottish Blackface lambs; that is, Suffolk lambs expressed greater environmental sensitivity than the Scottish Blackface.

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Effects of two dried forages, and a choice between them, on intake, growth and carcass composition in lambs of two breeds and their cross

Animal Science ◽

10.1017/s1357729800058884 ◽

2004 ◽

Vol 78 (3) ◽

pp. 485-496 ◽

Cited By ~ 8

Author(s):

J. M. Macfarlane ◽

R. M. Lewis ◽

G. C. Emmans

Keyword(s):

Food Intake ◽

Live Weight ◽

Carcass Composition ◽

X Ray ◽

Breed Type ◽

X Ray Computed ◽

Forage Type ◽

The Mean ◽

Mature Size ◽

Lamb Growth

AbstractThe effects of forage type, breed type and sex on lamb growth and carcass composition, and their changes throughout growth, were measured. The three breed types were Scottish Blackface (no. = 31), Suffolk (no. = 28) and their reciprocal cross (no. = 30). The lambs were given ad libitum a pelleted ryegrass alone, pelleted lucerne alone or a choice of both. Each lamb was scanned using X-ray computed tomography to measure the weights of fat, lean and bone in the carcass at three proportions of mature body weight (0·30, 0·45 and 0·65). Live weights and food intake data were recorded weekly. Average daily gains in live weight and carcass tissues, food intake and efficiency were calculated for each lamb between degrees of maturity. Relationships between weight and food intake were investigated using a Spillman function.Breed type had no effect on fat or lean proportion in the carcass but Scottish Blackface lambs had 1·04 times the carcass bone proportions of the Suffolk or crossbred lambs. Diet had no effect on carcass tissue proportions. The effect of sex on carcass composition changed with stage of maturity. Breed type and sex effects on intakes and gains in live weight and tissue weights were related to mature size differences. Scaling by (mature size)0·73did not fully remove these differences. There were no effects of breed type, sex or diet on efficiency. Lambs on ryegrass had lower intakes (0·878 as great) and slower growth (0·851 as fast) than those on lucerne or the choice treatment. The mean proportion of ryegrass in the choice diet was 0·366 (s.e. 0·0273); it increased slightly with time. There was no breed type by diet interaction for any of the variables examined. The Spillman function described growth well and showed that there were no effects of breed type, diet or sex on efficiency.

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Predicting carcass composition of terminal sire sheep using X-ray computed tomography

Animal Science ◽

10.1079/asc200647 ◽

2006 ◽

Vol 82 (3) ◽

pp. 289-300 ◽

Cited By ~ 21

Author(s):

J. M. Macfarlane ◽

R. M. Lewis ◽

G. C. Emmans ◽

M. J. Young ◽

G. Simm

Keyword(s):

Computed Tomography ◽

Lumbar Vertebrae ◽

Lumbar Vertebra ◽

Live Weight ◽

Carcass Composition ◽

The Body ◽

Thoracic Vertebrae ◽

X Ray ◽

X Ray Computed ◽

Terminal Sire

AbstractThe best means to utilize X-ray computed tomography (CT) and ultrasound to predict carcass lean, fat and bone weights in vivo in terminal sire sheep were tested. Data on 160 lambs from three breeds were considered: 50 Suffolk males, 50 Suffolk females, 40 Texel males and 20 Charollais males. One-fifth of the lambs within each breed and sex group were slaughtered at each of 14, 18 and 22 weeks of age and the remaining two-fifths at 26 weeks. Carcasses were dissected into lean, fat and bone weights. Prior to slaughter all lambs were CT scanned, with cross-sectional scans taken at seven sites along the body (ischium, hip, mid shaft of femur, 2nd and 5th lumbar vertebrae and 6th and 8th thoracic vertebrae), and ultrasound scanned at the 3rd lumbar vertebra and 13th rib.A set of three CT scans that reliably predicted carcass lean, fat and bone weights was identified which included a scan in each of the three main carcass regions: ischium in the hind leg, 5th lumbar vertebra in the loin and 8th thoracic vertebra in the shoulder. Breed and sex affected the intercepts of the prediction equations but not their slopes. Therefore, a minimal set of equations is likely to be sufficient to predict tissue weights, at least within terminal sire sheep breeds. Equations derived showed high degrees of fit to the data with R2values of 0·924, 0·978 and 0·830 for lean, fat and bone weights, respectively, when predicted using CT alone, and 0·589 and 0·857 for lean and fat weights, respectively, when predicted using ultrasound alone. Using live weight in addition to CT information only improved prediction accuracy slightly for lean (0·966) and fat (0·986) although more substantially for bone (0·925). Where live and tissue weights are considered contemporaneously in genetic evaluations, excluding live weight from prediction may therefore be preferable to avoid colinearity among weight measures.

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Effects of food quality on growth and carcass composition in lambs of two breeds and their cross

Animal Science ◽

10.1017/s1357729800058768 ◽

2004 ◽

Vol 78 (3) ◽

pp. 355-367 ◽

Cited By ~ 14

Author(s):

R. M. Lewis ◽

J. M. Macfarlane ◽

G. Simm ◽

G. C. Emmans

Keyword(s):

Food Intake ◽

Food Quality ◽

Live Weight ◽

Carcass Composition ◽

Free Access ◽

Food Effects ◽

X Ray ◽

Breed Difference ◽

X Ray Computed ◽

Lamb Growth

AbstractThe effects of food quality, breed type and sex (ram and ewe) on lamb growth and carcass composition, and their changes throughout growth, were measured. The three breed types were Scottish Blackface (B; no. = 24), Suffolk (S; no. = 28) and their reciprocal crosses (X; no. 33). The lambs had free access to a nutritionally non-limiting food, H, or a bulky food, L. Each lamb was scanned using X-ray computed tomography to measure the weights of fat, lean and bone in the carcass at three degrees of maturity (0.30,0.45 and 0.65) in live weight. Live weight and food intake data were recorded weekly. Average daily gains in live weight (ADG) and carcass tissues, intake (ADI) and efficiency (EFF = ADG/ADI) were calculated for each lamb between degrees of maturity. Gompertz and Spillman functions were used to investigate relationships between weight and both time and cumulative food intake.There was a breed by food interaction for fat and lean proportions (P < 0.05). Only on H was there a breed difference (P < 0.05) with S having less fat and more lean than either B or X, which did not differ from each other (P > 0.1). On food L there were no breed effects (P > 0.1). Across breeds, sexes and stages of maturity, food L caused lambs to have 0.810 as much fat and 1.063 as much lean compared with H (P < 0.001). There were breed by food interactions for ADG (P < 0.05) and EFF (P < 0.01). ADG on L was 0.72 of that on H for S, as compared with 0.79 for B and X. EFF on L was 0.463 of that on H for S, as compared with 0.586 for B and X. These were such that S was more sensitive to food effects on growth. The Gompertz and Spillman functions described growth well.

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X-ray computed tomography accurately assesses beef carcass composition

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200029574 ◽

2009 ◽

Vol 2009 ◽

pp. 118-118

Author(s):

E A Navajas ◽

C A Glasbey ◽

A V Fisher ◽

D W Ross ◽

J J Hyslop ◽

...

Keyword(s):

Computed Tomography ◽

Ct Scanning ◽

Spiral Ct ◽

Carcass Composition ◽

Automatic Image Analysis ◽

Independent Dataset ◽

X Ray ◽

X Ray Computed ◽

Novel Method ◽

Beef Carcass

X-ray computed tomography (CT) scanning of live animals and carcasses provides a very accurate assessment of the weights of fat, muscle and bone in pigs (Dobrowolski et al., 2003) and sheep (Johansen et al., 2007). Although the limiting size of the CT gantry prevents CT scanning of live beef cattle, beef primal joints are small enough to be scanned. Navajas et al. (2008) explored the use of spiral CT scanning (SCTS) to quantify beef carcass composition. The automatic image analysis developed provided very accurate assessments of primal and carcass composition (Navajas et al, 2008). The objective of this study was to evaluate the accuracy of this novel method for assessing beef primal cut and carcass composition in an independent dataset.

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Two methods of using X-ray Computed Tomography to predict carcass composition in sheep

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200009534 ◽

2005 ◽

Vol 2005 ◽

pp. 42-42

Author(s):

J. M. Macfarlane ◽

R. M. Lewis ◽

G. C. Emmans ◽

J.M. Young ◽

G. Simm

Keyword(s):

Computed Tomography ◽

Ct Scanning ◽

Carcass Composition ◽

The Body ◽

Anatomical Landmarks ◽

Cross Sectional ◽

X Ray ◽

X Ray Computed ◽

Breed Selection ◽

The Individual

X-ray computed tomography (CT) can be used to accurately assess carcass composition in sheep (Sehested, 1984; Young et al., 2001) both in research and commercially, as part of a breed selection programme. Two different CT scanning methods have been used: a) the reference scan method where tissue weights are predicted from tissue areas in a small set of cross-sectional scans at ‘anatomical landmarks’, and b) the Cavalieri method where a larger number of scans are taken along the body. It is of interest to examine the accuracy of evaluations made using these two methods and the individual merits of the two methods depending on their application.

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Genetic relationships between muscle density, measured by X-ray computed tomography (CT), and lamb growth and carcass traits

Advances in Animal Biosciences ◽

10.1017/s2040470010002773 ◽

2010 ◽

Vol 1 (1) ◽

pp. 134-134

Author(s):

N R Lambe ◽

J Conington ◽

E A Navajas ◽

K A McLean ◽

R Roehe ◽

...

Keyword(s):

Computed Tomography ◽

Genetic Relationships ◽

Carcass Traits ◽

Muscle Density ◽

X Ray ◽

X Ray Computed ◽

Lamb Growth

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Associations between beef density by X-ray computed tomography, intramuscular fat and fatty acid composition: preliminary results

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200029562 ◽

2009 ◽

Vol 2009 ◽

pp. 117-117

Author(s):

E A Navajas ◽

R I Richardson ◽

C A Glasbey ◽

N Prieto ◽

D W Ross ◽

...

Keyword(s):

Computed Tomography ◽

Image Analysis ◽

Fatty Acid ◽

Intramuscular Fat ◽

Carcass Composition ◽

Eating Quality ◽

X Rays ◽

Muscle Density ◽

X Ray ◽

X Ray Computed

X-ray computed tomography (CT) scanning makes use of the different rates at which the tissues attenuate X-rays depending on their densities. CT muscle density (MD) is the average pixel value for this tissue in the CT images and is related to real density of the tissue, which depends on its chemical composition. One of the components determining muscle density is intramuscular fat (IMF). Studies in sheep have shown that MD, measured in vivo, was phenotypically and genetically correlated to IMF and to fatty acid (FA) composition in Scottish Blackface lambs (Karamichou et al. 2006). Intramuscular fat and FA are important traits to measure due to their association with the nutritional value and eating quality of meat. A novel automatic image analysis for spiral CT scans (SCTS) of beef primal cuts allows very accurate estimations of primal cut and carcass composition with R2 of 0.90 to 0.99 (Navajas et al., 2008). The aim of this study was to investigate the associations of MD of beef primal cuts with IMF and FA profile in Aberdeen Angus (AA) and Limousin (LIM) cattle, based on the CT thresholds estimated as part of the development of the image analysis described by Navajas et al. (2008).

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