Effects of birth-rearing type on weaning weights in meat sheep are systematically associated with differences in mean performance among flocks

Table 1 Distribution of observations among dam age classes and among birth (TB) or birth-rearing (TBR) types for birth and weaning weights

Weight	Data set	Number of flocks	Number of observations	Effect	Effect class	Number of observations per class	Number of observations per flock
Weight	Data set	Number of flocks	Number of observations	Effect	Effect class	Number of observations per class	Median	Minimum	Maximum
Birth	Core	23	24 621	TB	1	4640	162	60	905
					2	15 718	556	269	2034
					3	4263	159	50	490
				Dam age	2	7140	242	122	889
					3 to 6	17 481	636	298	2339
				Lamb sex	Females	12 165	429	218	1591
					Males	12 456	461	221	1637
	Yearling dams^a	15	18 211	Dam age	1	2952	152	59	687
					3 to 6	10 465	535	183	2061
	Aged dams^b	17	23 430	Dam age	>6	2328	98	54	438
					3 to 6	15 134	757	302	2339
Weaning	Core	28	19 476	TBR	11	5002	142	45	877
					22	14 474	410	227	1705
				Dam age	2	6166	173	89	695
					3 to 6	13 310	367	174	1581
	TBR = 33^c	20	17 438	TBR	33	1577	58	30	202
					22	11 775	503	227	1705
	Yearling dams^a	15	14 869	Dam age	1	2545	140	50	548
					3 to 6	8265	431	174	1581
	Aged dams^b	10	11 835	Dam age	>6	1230	97	53	309
					3 to 6	7444	589	286	1581

^aIncludes flocks from the core dataset that have at least 50 records on yearling dams. These datasets were restricted to only single and twin lambs but included lambs with 2-year-old dams. Numbers are shown only for the target and reference dam age classes
^bIncludes flocks from the core dataset that also have at least 50 records on > 6-year-old dams
^cIncludes flocks from the core dataset that also have at least 30 records for lambs with TBR = 33. This dataset was restricted to only 2-year-old and adult dams but included lambs with TBR = 11. Numbers are shown only for the target and reference birth-rearing types

ISSN: 1297-9686