A meta-analysis on the effect of the feeding type and production system on the carcase quality of lambs

Figures & data

Table 1. Body characteristics of the most common sheep breeds in the world.

Breed	Type	Adult size	Weight at slaughter, kg	Carcass weight, kg	Carcass yield performance, %
Blackbelly	Early	Small	35	15.75	45
Border Leicester	Later	Big size	45	22.50	50
Cheviot	Early	Small	35	16.80	48
Charollais	Early	Medium+	45	23.40	52
Colombia	Later	Big size	50	26.50	53
Dorper	Early	Medium	45	23.40	52
Dorset	Intermediate	Medium+	50	26.00	52
Hampshire	Intermediate	Big size	50	26.50	53
Katahdin	Intermediate	Medium	40	20.00	50
Meriano	Intermediate	Medium−	45	22.50	50
Pelibuey	Intermediate	Medium+	45	22.05	49
Rambouillet	Later	Big size−	50	26.00	52
Rommey Mash	Intermediate	Medium+	45	22.50	50
Polypay	Intermediate	Medium+	45	22.95	51
Romanov	Early	Small	35	16.80	48
Southdown	Intermediate	Medium−	40	20.40	51
Suffolk	Later	Big size	50	25.50	53
Texel	Intermediate	Medium+	45	22.90	51

Adapted from Partida et al. (2013).

Figure 1. Forest plot diagram of the effect on the characteristics on the slaughter in carcase lambs fed with and without supplement. The x-axis shows the difference of standardised means (standardised by the z-statistic); therefore, the points to the left of the line represent a reduction in the trait, while the points to the right of the line indicate an increase. Each square represents the size of the mean effect of that study, and the size of the square reflects the relative weight of the study of the overall estimate of effect size with the larger squares representing a larger weight. The upper and lower bound of the squared line represents the upper and lower confidence intervals of 95% for the size of the effect. The diamond at the bottom represents the 95% confidence interval for the global estimate, and the vertical line of points represents the mean difference of zero or no effect.

Figure 2. Forest plot diagram of the effect on the hot carcase weight (HCW) in lambs fed with and without supplement. The x-axis shows the difference of standardised means (standardised by the z-statistic); therefore, the points to the left of the line represent a reduction in the trait, while the points to the right of the line indicate an increase. Each square represents the size of the mean effect of that study, and the size of the square reflects the relative weight of the study of the overall estimate of effect size with the larger squares representing a larger weight. The upper and lower bound of the squared line represents the upper and lower confidence intervals of 95% for the size of the effect. The diamond at the bottom represents the 95% confidence interval for the global estimate, and the vertical line of points represents the mean difference of zero or no effect.

Figure 3. Forest plot diagram of the effect on the cold carcase weight (CCW) in lambs fed with and without supplement. The x-axis shows the difference of standardised means (standardised by the z-statistic); therefore, the points to the left of the line represent a reduction in the trait, while the points to the right of the line indicate an increase. Each square represents the size of the mean effect of that study, and the size of the square reflects the relative weight of the study of the overall estimate of effect size with the larger squares representing a larger weight. The upper and lower bound of the square line represents the upper and lower confidence intervals of 95% for the size of the effect. The diamond at the bottom represents the 95% confidence interval for the global estimate, and the vertical line of points represents the mean difference of zero or no effect.

Figure 4. Forest plot diagram of the effect on the area of longissimus dorsi (ALd) in lambs fed with and without supplement. The x-axis shows the difference of standardised means (standardised by the z-statistic); therefore, the points to the left of the line represent a reduction in the trait, while the points to the right of the line indicate an increase. Each square represents the size of the mean effect of that study, and the size of the square reflects the relative weight of the study of the overall estimate of effect size with the larger squares representing a larger weight. The upper and lower bound of the square line represents the upper and lower confidence intervals of 95% for the size of the effect. The diamond at the bottom represents the 95% confidence interval for the global estimate, and the vertical line of points represents the mean difference of zero or no effect.

Figure 5. Forest plot diagram of the effect on the subcutaneous fat thickness lambs fed with and without supplement. The x-axis shows the difference of standardised means (standardised by the z-statistic); therefore, the points to the left of the line represent a reduction in the trait, while the points to the right of the line indicate an increase. Each square represents the size of the mean effect of that study, and the size of the square reflects the relative weight of the study of the overall estimate of effect size with the larger squares representing a larger weight. The upper and lower bound of the squared line represents the upper and lower confidence intervals of 95% for the size of the effect. The diamond at the bottom represents the 95% confidence interval for the global estimate, and the vertical line of points represents the mean difference of zero or no effect.

Figure 6. Forest plot diagram of the effect on the final body weight (FBW) (kg) in lambs fed in Feed-Lot or Free Range systems. The x-axis shows the difference of standardised means (standardised by the z-statistic); therefore, the points to the left of the line represent a reduction in the trait, while the points to the right of the line indicate an increase. Each square represents the size of the mean effect of that study, and the size of the square reflects the relative weight of the study of the overall estimate of effect size with the larger squares representing a larger weight. The upper and lower bound of the square line represents the upper and lower confidence intervals of 95% for the size of the effect. The diamond at the bottom represents the 95% confidence interval for the global estimate, and the vertical line of points represents the mean difference of zero or no effect.

Figure 7. Forest plot diagram of the effect on the hot carcase weight (HCW) in lambs fed in Feed-Lot or Free Range systems. The x-axis shows the difference of standardised means (standardised by the z-statistic); therefore, the points to the left of the line represent a reduction in the trait, while the points to the right of the line indicate an increase. Each square represents the size of the mean effect of that study, and the size of the square reflects the relative weight of the study of the overall estimate of effect size with the larger squares representing a larger weight. The upper and lower bound of the square line represents the upper and lower confidence intervals of 95% for the size of the effect. The diamond at the bottom represents the 95% confidence interval for the global estimate, and the vertical line of points represents the mean difference of zero or no effect.

Figure 8. Forest plot diagram of the effect on the cold carcase weight (CCW) in lambs fed in Feed-Lot or Free Range systems. The x-axis shows the difference of standardised means (standardised by the z-statistic); therefore, the points to the left of the line represent a reduction in the trait, while the points to the right of the line indicate an increase. Each square represents the size of the mean effect of that study, and the size of the square reflects the relative weight of the study of the overall estimate of effect size with the larger squares representing a larger weight. The upper and lower bound of the square line represents the upper and lower confidence intervals of 95% for the size of the effect. The diamond at the bottom represents the 95% confidence interval for the global estimate, and the vertical line of points represents the mean difference of zero or no effect.

Figure 9. Forest plot diagram of the effect on the area of the longissimus dorsi in lambs fed in Feed-Lot or Free Range systems. The x-axis shows the difference of standardised means (standardised by the z-statistic); therefore, the points to the left of the line represent a reduction in the trait, while the points to the right of the line indicate an increase. Each square represents the size of the mean effect of that study, and the size of the square reflects the relative weight of the study of the overall estimate of effect size with the larger squares representing a larger weight. The upper and lower bound of the squared line represents the upper and lower confidence intervals of 95% for the size of the effect. The diamond at the bottom represents the 95% confidence interval for the global estimate, and the vertical line of points represents the mean difference of zero or no effect.

Figure 10. Forest plot diagram of the effect on the subcutaneous fat thickness in lambs fed in Feed-Lot or Free Range systems. The x-axis shows the difference of standardised means (standardised by the z-statistic); therefore, the points to the left of the line represent a reduction in the trait, while the points to the right of the line indicate an increase. Each square represents the size of the mean effect of that study, and the size of the square reflects the relative weight of the study of the overall estimate of effect size with the larger squares representing a larger weight. The upper and lower bound of the square line represents the upper and lower confidence intervals of 95% for the size of the effect. The diamond at the bottom represents the 95% confidence interval for the global estimate, and the vertical line of points represents the mean difference of zero or no effect.

Table 2. Effect of the supplement on the carcase characteristics of lambs.

Item	Number of trials, n	Raw mean difference	Effect size	Random model		Mixed model^a
				I^2	p Value	I^2	p Value
FBW, kg	19	2.40	1.40	97.90	.01	89.00	.01
HCW, kg	15	3.20	2.50	98.20	.01	87.00	.01
CCW, kg	15	2.20	2.40	98.10	.01	91.00	.01
ALd, cm^2	9	1.00	0.60	87.70	.01	76.00	.01
SFT, mm	13	2.00	1.40	95.40	.04	86.00	.01

I² = heterogeneity as a percentage of total variability.

FBW: final body weight; HCW: hot carcase weight; CCW: cold carcase weight; ALd: area of longissimus dorsi; SFT: subcutaneous fat thickness.

^a Fixed effects or moderator variables of the mixed model were: geographical region (Intertropical Zone, Northern Hemisphere Zone and Hemisphere South Zone), country, breed and adult size (small, medium and big).

Significance was accepted as P < 0.05.

Table 3. Effect of the production system (feedlot or free-range) on the carcase characteristics in lambs.

Item	Number of trials, n	Raw mean difference	Effect size	Random model		Mixed model
				I^2	p Value	I^2	p value^a
FBW, kg	17	3.20	1.50	98.10	.01	89.0	.01
HCW, kg	15	3.80	2.90	98.20	.01	89.0	.01
CCW, kg	11	2.80	2.80	92.00	.01	92.0	.01
ALd, mm^2	9	1.90	1.20	83.00	.01	76.4	.01
SFT, mm	11	2.50	1.20	95.50	.01	85.0	.01

I² = heterogeneity as a percentage of total variability.

FBW: final body weight; HCW: hot carcase weight; CCW: cold carcase weight; ALd: area of Longissimus dorsi; SFT: subcutaneous fat thickness.

^a Fixed effects or moderator variables of the mixed model were: geographical region (Intertropical Zone, Northern Hemisphere Zone and Hemisphere South Zone), country, breed and adult size (small, medium and big).

Significance was accepted as P < 0.05.

Partida PJA, Braña VD, Jiménez SH, Ríos RFG, Buendía RG. 2013. Producción de carne ovina. Centro nacional de investigación disciplinaria en fisiología y mejoramiento animal. Ajuchitlán Qro Libro Técnico INIFAP. 5:68.

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