Introduction

There are a number of important reasons that sow nutritional performance during lactation is of great interest to producers.

In a series of excellent extension articles, Flowers (2002a,b) indicated that, when troubleshooting reproductive problems in sows, a key event to investigate carefully is feed intake of the sow during her previous lactation.

Besides the reproductive performance of the sow, piglet performance is also intrinsically associated with the nutritional status and, as a result, milk production, of its dam (Noblet and Etienne, 1989). Piglets that are weaned greater than 3.5kg have a three times higher chance of surviving to market and an 8.5 times higher chance of not being lightweight at 10 weeks of age (Larriestra et al. 2005).

An element of how a sow performs during lactation has to do with the gestational feeding program that is in place (Koketsu et al., 1996; Quinioiu, 2005).

There has been some interesting work on feeding during gestation (Young et al. 2004). These data have resulted in extension materials being developed recommending feeding according to gestating sow weight and back fat thickness rather than simply body condition score (Aherne, 2008b).

With this method, Young et al. (2004) found no improvement in subsequent lactation performance but did find the program did result in fewer over-conditioned sows and less feed cost per sow annually. As well, by increasing feed allotment during late gestation sows experienced easier farrowing but no improvement in sow or piglet performance (Quiniou, 2005).

Koketsu et al. (1996) analyzed a large PigChamp database and found many factors to be related to the average daily feed intake of a sow. Pattern of consumption, litter size, lactation length, parity, gestation feeding program and environment, i.e. temperature and humidity, all were shown to affect average daily feed intake by sows (Koketsu et al. 1996). Vignola (2009) summarised a number of other principles or factors that affect feed intake of nursing sows:

1. Too restrictive feed allowance
2. Water intake (both in the feed (as gruel) and as a separate fresh drinking source)
3. Employee stockmanship skills and
4. Animal comfort/equipment management.

Some of these factors, when controlled, have been shown to affect sow feed intake and lactation performance, for example, water intake and temperature (Leibbrandt et al., 2001).

A number of strategies have been developed in efforts to reduce the risk of a drop in feed intake for nursing sows. While there are extension publications readily available explaining the “best” system, there has been very little experimental data published to compare these methods. Aherne (2008a) explained a method of slowly increasing feed intake up to a target (4 lb + 1.25lb per piglet) by day 8 and holding that intake level until day 12 (which coincides with the time of high risk to go off feed seen by Koketsu (2006)). On day 13, Aherne (2008a) recommended feeding ad libitum. Another method that appears to be popular is feeding ad libitum for the entire lactation. Finally, a method being recommended by some (Loula, 2009) is a variation of the last method where the sow can “self-feed” by dispensing feed into her trough by turning a wheel.

To the author's knowledge, no work has been done to investigate the three methods of feeding lactating sows side-by-side. Nor has there been any published work to investigate the interaction of the methods of feeding gestating sows and lactating sows on a sow’s nutritional, metabolic and reproductive performance and resulting litter performance to weaning.

Understanding the strengths and weaknesses of various feeding regimes for gestating and nursing sows and being able to monitor their nutritional/metabolic health will be of benefit in reducing pre-weaned mortalities and increasing weaning weight in piglets as well as improving the sow’s subsequent reproductive performance.

Animals and Treatments

Three hundred sows were randomly assigned (after being balanced for parity) to six treatments set up in a 2×3 factorial design.

There were two types of gestational feeding:

• The first (“Conv.”) was a typical method where the producer does a visual appraisal of the sow’s condition and sets a feed amount based upon that visual inspection.
• The second (“Kansas”) was the system as promoted by the Kansas State Swine Extension group (Young et al. 2004) where sows are weighed and their back fat is measured using an ultrasound. Feed amounts are set based on a table that can be customised for the energy density of the diet and number of feedings per day (one in this case).

There were three types of lactation sow feeding.

• The first (“Conv.”) was feeding as much as the sow wishes (ad libitum) from day 3 onward. The goal was that there was always a little feed left in the feed trough when the next feeding occurred.
• The second (“Ramp”) was such that the amount is slowly ramped up to ad libitum over 13 days. On day 1, sows received 2.0 kg of feed, on days 2 and 3 sows received 3.0kg of feed. From days 4 to 8, sows were ramped up as quickly as possible to 1.8 kg + 0.6kg per piglet of feed. When this target level was attained, it was maintained until day 12. From day 13 onwards, the sow was fed ad libitum. This method was recommended by Aherne (2008a).
• The third (“Ad libitum”) feeding method was self-feeders where the sow could decide for herself how much she would like to consume from day 1 to weaning.

The treatments were applied over three parities in order to determine what the longer term effects of the various feeding regimes would be. All sows were fed the same diets across treatments (gestating and lactating rations).

Data Collection and Analyses

Feed intake and sow and piglet mortality events were recorded on a daily basis. Piglets were weighed at birth and again at weaning. Sows were ultrasounded for back fat when moved into the farrowing crate and again after weaning. Feed samples were collected on a monthly basis. Sow weights were recorded when moved into the farrowing crate, as soon after farrowing as possible (usually same day or the next day) and when moved out of the farrowing crate.

Reproductive parameters (weaning-to-oestrus interval, farrowing rate, litter size (alive, stillborn and mummified)) were recorded for each parity. All data were analysed using the Mixed procedure of SAS. Repeated measures were conducted on all data that were measured repeatedly over time. Factors of interest are: sow feed intake, back fat changes, piglet performance and reproductive performance of sows.

Results

At time of submission of this article all of the data have not been analyzed but Table 1 is a summary of some of the data.

Table 1. Sow feed intake, body weight and litter size and piglet weight data
	Gestational feeding system		Lactational feeding system
	Conv. 3	Kansas	Conv	Ramp	Ad libitum
Sow feed intake (kg/d)
- Day -7 to -1	3.14 (0.01) a	3.15 (0.01) a	3.14 (0.01) x	3.15 (0.01) x	3.14 (0.01) x
- Day 0 to 21	6.50 (0.03) a	6.38 (0.03) b	6.44 (0.03) xy	6.52 (0.03) x	6.35 (0.03) y
Sow bodyweight (kg) after 1st period
- In crate	248.2 (2.1) a	254.2 (2.2) b	252.6 (2.6) x	253.1 (2.6) x	247.9 (2.6) x
- Farrowing	237.9 (2.2) a	243.9 (2.0) b	243.3 (2.5) x	241.7 (2.4) x	237.6 (2.5) x
- Weaning	232.3 (1.7) a	236.5 (1.7) b	234.7 (2.1) x	236.8 (2.1) x	231.7 (2.1) x
Sow bodyweight change (kg) after 1st period
- In crate to weaning	-16.5 (1.3) a	-18.2 (1.3) a	-18.5 (1.6) x	-16.5 (1.6) x	-17.0 (1.6) x
- In crate to farrowing	-11.2 (1.0) a	-11.2 (1.0) a	-9.9 (1.3) x	-12.2 (1.2) x	-11.4 (1.2) x
- Farrowing to weaning	-6.0 (1.2) a	-7.7 (1.2) a	-9.5 (1.4) x	-4.8 (1.4) y	-6.3 (1.4) xy
Litter size (live) after 1st period
- At birth	12.9 (0.4) a	12.9 (0.4) a	12.2 (0.5) x	12.5 (0.5) xy	14.0 (0.5) y
- At cross-fostering	12.3 (0.1) a	12.2 (0.1) a	12.3 (0.1) x	12.2 (0.1) x	12.3 (0.1) x
- At weaning	11.3 (0.1) a	11.1 (0.1) a	11.2 (0.1) x	11.2 (0.1) x	11.1 (0.1) x
Piglet age and growth data
- Age (d) at 1st weighing	1.6 (0.1) a	1.6 (0.1) a	1.6 (0.1) x	1.6 (0.1) x	1.6 (0.1) x
- Weight (kg) at 1st weighing	1.61 (0.02) a	1.62 (0.02) a	1.65 (0.02) x	1.61 (0.02) x	1.59 (0.02) x
- Standard deviation (kg) of weights at 1st weighing	0.20 a	0.20 a	0.20 x	0.20 x	0.19 x
- Age (d) at 2nd weighing	19.9 (0.1)a	19.8 (0.1) a	19.9 (0.2) x	19.9 (0.2) x	19.9 (0.1) x
- Weight (kg) at 2nd weighing	5.85 (0.04) a	5.81 (0.04) a	5.84 (0.05) xy	5.92 (0.05) x	5.72 (0.05) y
- Standard deviation (kg) of weights at 2nd weighing	0.85 a	0.84 b	0.83 x	0.85 x	0.85 x
1 Differences in gestational system with different superscript (a,b) are different (P<0.10) 2 Differences in lactational system with different superscript (x,y) are different (P<0.10) 3 Treatments descriptions are in paragraph “Animals and Treatments”.

Discussion

None of the statistical differences seen was remarkable but until the economics of the differences are determined we must be careful to pass them off as not important. The difference in feed intake during lactation for the two gestational treatments is interesting.

Until we get the gestation data all analysed it is difficult to make any substantial conclusions. It appears the slow ramp-up method recommended by Aherne (2008a) resulted in the largest feed intake for the lactating sows. This, coupled with the combination of lowest bodyweight loss during lactation and piglet weaning weight for that treatment, makes this system positive especially for farms where sows lose concerning amounts of body weight during lactation.

The conventional system of lactational feeding resulted in the largest body weight loss during lactation but also resulted in comparable weaning weights in piglets. The ad libitum system of feeding during lactation resulted in the largest litter size at birth (past the first period/trial parity) but unfortunately, because the cross-fostering that was completed on the farm what impact it would have accumulated in over lactations may have been confounded.

The companion paper to this one, by Dale Rozeboom (2014), delves into nutritional requirements during the critical periparturient period.

Acknowledgement: The author acknowledges funding from the Ontario Ministry of Agriculture and Ontario Pork for this project, as well as the cooperation and dedication of the owners and employees of Bartside Farms where the trial took place.

References

• Aherne, F.X. 2008a. Feeding the lactating sow. Pork Industry Handbook. PIH 07-01-05.
• Aherne, F.X. 2008b. Feeding the gestating sow. Pork Industry Handbook. PIH 07-01-06.
• Flowers, W.L. 2002a. Using reproductive physiology to troubleshoot fertility problems (Part I). Swine News NC State Swine Extension 25, 7.
• Flowers, W.L. 2002b. Using reproductive physiology to troubleshoot fertility problems (Part II). Swine News NC State Swine Extension 25, 8.
• Koketsu, Y., Dial, G.D., Pettigrew, J.E. and King, V.L. 1996. Feed intake pattern during lactation and subsequent reproductive performance of sows. J Anim Sci 74:2875-84.
• Larriestra, A.J., Maes, D.G., Deen, J. and Morrison, R.B. 2005. Mixed models applied to the study of variation of grower-finisher mortality and culling rates of a large swine production system. Can J Vet Res 69:26-31.
• Leibbrandt, V.D., Johnston, L.J., Shurson, G.C., Crenshaw, J.D., Libal, G.W. and Arthur, R.D. 2001. Effect of nipple drinker water flow rate and season on performance of lactating swine. J Anim Sci. 7:2770-75.
• Loula, T. 2009. Keynote address: Marketing into the Future. 47th Annual Southwestern Ontario Pork Conference. Ridgetown, Ontario.
• Noblet, J. and Etienne, M. 1989. Estimation of sow milk nutrient output. J Anim Sci 67:3352-9.
• Quiniou, N. 2005. Influence de la quantité d’aliment allouée à la truie en fin de gestation sur le déroulement de la mise bas, la vitalité des porcelets et les performances de lactation. Journées de Recherche Porcine 37:187-194.
• Rozeboom, D.W. 2014. Feeding the sow: peri-partum. Proceedings of the 14th London Swine Conference, in press
• Vignola, M. 2009. Sow feeding management during lactation. Proceedings of the 9th London Swine Conference p107-117.
• Young, M.G., Tokach, M.D., Aherne, F.X., Main, R.G., Dritz, S.S., Goodband, R.D. and Nelssen, J.L. 2004. Comparison of three methods of feeding sows in gestation and the subsequent effects on lactation performance. J Anim Sci 82:3058-70.

Reference

Luimes P.H. 2014. Feeding the sow: Comparison of gestational and lactation programmes. Proceedings of the London Swine Conference. London, Ontario, Canada. 26 to 27 March 2014. p45-49.

October 2014