Sheep linear measurements

Environmental and genetic effects on lambs from birth to 12 months of age
Correlations between weight and linear measurements
Repeatability of early lamb measurements

Environmental and genetic effects on lambs from birth to 12 months of age

Three linear measurements, height at withers, scapulo-ischial length, and heart girth, together with body weight were available for 360 lambs at birth, 2 and 4 months; 298 at 4, 6 and 8 months; and 209 at 8, 10 and 12 months. Analyses of variance laid out in Table 23 show the significance of environmental and genetic effects on the linear measurements and weight from birth to 12 months. The general situation is that these effects on linear measurements fairly closely resembled their effects on body weight.

The estimated least squares means for height, length, girth and weight at birth 2, 4, 6, 8, 10 and 12 months are given in Table 24.

Figure 5. Mean changes in linear measurements and weight.

Table 23. Analysis of variance of weight and linear measurements at seven different ages

Table 24. Estimated least squares means for weights and linear measurements at seven different ages.

Table 25. Estimated least squares means for weights and linear measurements at seven different ages.

Figure 5 illustrates the mean changes in linear measurements and weights from birth to 12 months of age. The coefficient of variation of each of the three linear measurements at all stages was about 8%, while that of weight was around 20%.

Correlations between weight and linear measurements

Table 25 presents the correlations between weight and height, length and girth. All were significant.

Table 25. Correlations between linear measurements and weight

Age	No.	Correlations between weight and:
		Height	Length	Girth
Birth	360	0.56	0.43	0.72
2 months	360	0.74	0.80	0.84
4 months	360	0.81	0.77	0.91
4 months	298	0.81	0.74	0.91
6 months	298	0.78	0.75	0.89
8 months	298	0.60	0.86	0.88
8 months	209	0.66	0.82	0.88
10 months	209	0.64	0.82	0.80
12 months	209	0.65	0.79	0.88

Repeatability of early lamb measurements

The repeatabilities of lamb linear measurements at birth, 2 and 4 months considered as a characteristic of the ewe are indicated in Table 26.

Table 26. Repeatability of lamb linear measurements

	Height		Length		Girth
	r	s.e.	r	s.e.	r	s.e.
Birth	0.18	0.07	0.21	0.07	0.17	0.07
2 months	0.16	0.07	0.25	0.07	0.32	0.06
4 months	0.26	0.07	0.18	0.07	0.32	0.07