Edward Carl Schultz joins Dr. Prem Kharbanda (Edmonton) and Tom Livingston (Duchess) as Agriculture Hall of Fame inductees in 2008. I am/was personally familiar with ten of the inductees, through my own lengthy pig work in Alberta.

Banff in Autumn 2008

There is considerable disagreement as to the effects of age, weight, and backfat levels at first breeding on longevity and/or lifetime performance. The results of several large surveys and many experiments have shown that under good feeding and management conditions there is no significant difference in longevity or lifetime productivity between gilts bred at 5 -10 months of age, 85 - 155 kg or 9 - 25 mm P2 backfat thickness. In some surveys, earlier breeding actually increased longevity and lifetime productivity (Table 1.) As can be seen in this large data set, breeding as late as 9 and 10 months of age actually reduces lifetime production.

Table 1. Effect of age at first service on longevity and number of pigs born live)

Age at first service (months)	6	7	8	9	10	11
No. parities before culling	3.50	3.45	3.47	3.25	3.18	3.07
No. born alive/lifetime	34.8	34.3	35.1	34.0	32.2	31.5

31,800 PigChamp records (Culbertson and Mabry 1995)

The data from 2357 records of line 42 PIC sows also supports the view that earlier breeding does not reduce longevity or productivity in well managed herds (Table 2).

Table 2. Effects of age and breeding on longevity and performance

Range in service age, days	135-165	166-195	196-225	226-255
Entry age, days	141	160	176	197
Average service age, days	158	183	209	238
Entry to conception, days	25.7	28.8	35.0	45.0
Total live born/litter	10.25	10.82	10.95	10.35
Total live born/lifetime	41.50	43.03	44.80	41.20
Removed, parity	4.05	4.00	4.09	3.63
Number of animals	83	820	907	394

2,357 records, L42 PIC sows (Alberta Pig Company 2000)

In contrast, other data have shown that gilts of less than 120 kg or with less than 17 to 18 mm backfat at time of first breeding have lower survival rates and lower number of pigs produced per lifetime. It would appear that culling rate and lifetime productivity are very dependent on the quality of the facilities, management and nutritional program to which gilts are exposed. Therefore, any association between age, weight, or backfat level at breeding and longevity and/or lifetime performance is farm specific. A relationship between body composition (backfat) at mating and longevity merely reflects the consequences of not targeting the nutrition and management program for gilts to the age, weight, and backfat levels of the gilts at entry. Therefore, the best age, weight or backfat level at first breeding is not only farm and genotype specific but is actually in each farm.

Sow longevity

The lean contemporary genetics of today provide superior reproductive performance along with the capability of delivering high lean growth rate. The consequences of these genetic improvements are lower backfat at selection and breeding, heavier animals on younger legs and joints, and lower appetite in lactation. Management and feeding practices must be raised to a level appropriate to meet these new challenges.
A target of 4 to 6% sow mortality is achievable on most commercial units, regardless of size. But some herds are reporting levels of mortality of 10 to 15% while others have rates below 2%. Of equal concern is the increase in culling rates on many farms.

Frequently, culling rate targets are set at 35%-45% but are actually 50%-60%. Why is this, and what can we do about it? We should start this discussion by defining the various terms used. Mortality should only include natural deaths. Sows that have to be put down (euthanasia) on the farm should be differentiated. So record systems should differentiate between natural death, euthanasia, and culled sows, even though the end result is the same. However, for problem- solving purposes we need to differentiate. In fact, mortality records should be specific enough to include cause of death, parity, stage of production, season, and even day of the week and time of death. With this data your veterinarian may be able to detect a pattern or more easily diagnose the cause of the mortality.