Direct and correlated responses to selection for autumn lambing in sheep

Table 1 Descriptive statistics and data structure for ewe reproduction and lamb performance

Item	Ewe reproduction		Lamb performance
Item	Fertility^a	Litter size^b	Birth weight	60-day BW	90-d BW	120-day BW	60-day SC	90-day SC	120-day SC
Mean	0.49	1.75	3.6	19.7	28.8	37.2	13.6	20.0	25.7
Standard deviation	0.50	0.60	0.9	5.0	6.4	8.2	2.3	3.9	3.4
Maximum	1	1	6.4	35.5	48.2	60.6	20.7	30.8	32.5
Minimum	0	3	1.8	12.7	25.7	31.1	8.2	10.5	15.5
Number of records^c	2956	1443	2286	2493 (1858)	2082 (1536)	1312 (1312)	472	469	422
Number of ewes or dams^d	1048	591	588	541	484	467	247	250	230
Number of ewe or lamb sires^d	141	133	102	101	99	94	75	75	72
Average. number of records per ewe or dam^d	2.82	2.44	4.13	3.43	3.17	2.81	1.91	1.88	1.83

^aRealized fertility during the spring joining period = 1 for ewes that lambed in autumn and 0 for ewes that did not lamb
^bNumber of lambs born per ewe lambing
^cNumber of records for lamb BW is for both autumn- and spring-born lambs or, in parentheses, only autumn-born lambs; all other variables used only lambs born in autumn
^dNumber of ewes, number of ewe sires, and records per ewe for ewe reproduction; number of dams, number of dam sires, and records per dam for lamb performance
BW body weight (kg), SC scrotal circumference (cm)

ISSN: 1297-9686