I understand that the Federal sow elimination program is being taken up quite well by producers exiting the pork industry. Barns and herds that go out of pigs now will need to stay out for the next three years. It’s unfortunate that the program wasn’t implemented a year sooner, so that producers might have been prepared to return to the industry for the better pricing and profitability anticipated in 2009, 2010 and 2011.

High performance Lacombe boar

Lacombe boars averaged 128 Sire Line Index and 123 Dam Line Index on eight pigs probed May 2. Highest indexing gilt showed 177 SLI and 177 DLI. If we agree that hogs can reach market weight in 165 days, then Cayley Colony’s 25 market hogs (identified by notch) that went to slaughter at 260 pounds in 150 days is a great reflection on the high performance Yorkshire boars supplied by our F&S Hog Farm.

Non-productive Days as an Indicator of Breeding Herd Efficiency

Non-productive days (NPD) are days in which inventoried females are neither pregnant nor lactating. This includes any gilts that have been selected and are over normal market weight. NPD can be calculated as follows:

NPD = 365 – [L/F/Y x (LL + GL)]
where L/F/Y is litters per mated female per year
LL is lactation length in days
GL is gestation length in days

For a modern herd, an example might be: 2.4 litters/sow/year, with a 16 day lactation and 115 days in gestation.

NPD = 365 – [2.4 x (16 + 115)] = 51 days

For this herd, 14% of the sows are inactive (51/365) at any one time.

The components of NPD and their relative importance are show in the following table:

Component	Target, days	%Contribution to NPD
Gilts
Entry-to-first-service	<30	20
Entry-to-removal	<4	2
First service to conception	<3	3
First service to removal	<7	5
Sows
Weaning-to-service	<10	25
Weaning-to-removal	<3	8
First service to conception	<5	18
First service to removal	<7	19

From Dr. G. Dial 1994

Importance of parity distribution to pigs/sow/year

Parity	1	2	3	4	5	6+
No. born live	10.1	11.0	11.9	11.9	12.2	11.8
Farrowing rate %	88.6	90.6	91.9	91.2	92.1	82.6
No. born/bred sow	8.95	9.97	10.94	10.84	11.20	9.75

Herd data, 1250 sow herd

Targeted parity distribution

Parity	1	2	3	4	5	6	7
% of sows	20	18	17	16	14	10	5
% of sows parity 3, 4, 5 = 47%
% of sows parity 3 – 6 = 57%

As can be seen from the component table, the important contributors to NPD are entry-to-service interval, weaning-to-service interval and post-service intervals.

These post-service intervals are the time from service until she is detected as not being pregnant. Basically, NPD is a function of how long you keep gilts in the herd before you breed them; how good your farrowing rate is; how good your pregnancy detection system is; and how quickly you dispose of sows that are to be culled.

Increasing herd productivity: the role of the gilt

There are more gilts bred and farrowed than any other parity, and therefore, if entry to service periods are too long, gilts can contribute more than 30% of NPD within a herd. Also, if gilt litter size and farrowing rate are low, total herd productivity will be reduced.
Average replacement rates in Canada are about 48%, ranging from 28%-69%. The average number of litters per sow for these herds is 2.25, with the top 10% of herds farrowing 2.40 litters and the bottom 10% farrowing 2.10 litters/year. Gilt litters are 21% on average, ranging between 12% and 33%, using those average litter numbers

In the next article, we will discuss further the role of the gilt in breeding herd efficiency.