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Animal Welfare

Proper Lactation Feeding Critical to Sow Longevity

Adequate feeding throughout lactation is paramount to the maintenance and longevity of high-producing females in the breeding herd.

In a Pork Checkoff-funded study, 1,275 sows from a Minnesota herd were analyzed for the association of farrowing and lactation factors during lactation (including reported diseases) on the likelihood of removal from the herd before the next farrowing.

The effect of low daily feed intake (less than 9 lb.) for the first two weeks of lactation, on sow removals before next farrowing, was specifically addressed.

Overall, results indicated that the risk of sow removal declined as average daily feed intake and the number of piglets born alive increased.

The likelihood of removal from the herd dropped by 11% with every pound increase in average daily feed intake during lactation.

Also, the odds of removal from the herd decreased by 7% for every additional piglet born alive.

Parity 1 and 2 sows and Parity 3-5 sows had 47% and 44% less chance, respectively, of removal from the herd, compared to sows of Parity 6 or higher.

Other factors such as mummies, stillbirths, farrowing induction, farrowing assistance and reported diseases during lactation, didn't appear to influence sow longevity in this study.

Sows consuming less than 9 lb. of feed on a single day during the first two weeks of lactation had 27% greater chance of removal from the herd.

The study suggested that ensuring adequate feed intake from the start of lactation may reduce sow removals in breeding herds.

Deficient feed intake in sows results in excessive weight loss and may have adverse reproductive consequences, resulting in reduced sow longevity.

Researchers: Sukumarannair S. Anil, DVM; Leena Anil, DVM; and John Deen, DVM, University of Minnesota. Contact Sukumarannair S. Anil by phone (612) 625-4243, fax (612) 625-1210 or e-mail

Floor Space Requirements Lowered For Finishing Pigs

University of Illinois research has concluded that growth rates of finishing pigs can be optimized when housed at much lower floor space requirements than previously reported.

Two studies in a commercial wean-to-finish production system confirm that a space allowance of 7.3 sq. ft./pig will achieve maximum growth rates, compared to previous minimum requirements of 8.8-9.0 sq. ft./pig.

If implemented in grow-finish barns, these findings could increase throughput and provide new welfare guidelines for the pork industry.

Study 1 used 3,132 pigs grown from 75 lb. to 255 lb., allotted to three floor spaces: 6.6, 7.3 and 8 sq. ft./pig.

Study 2 used 1,740 pigs grown from weaning (about 17 days of age) to 265 lb., allotted to five floor spaces: 6.2, 6.6, 7.0, 7.4 and 7.9 sq. ft./pig.

Pigs were housed in groups of 29 pigs/pen, and pen sizes were adjusted to the required floor spaces.

Data on pig weights and feed delivery and disappearance were recorded for both studies.

Pigs at the lowest floor space (6.2 and 6.6 sq. ft./pig) had reduced growth rates in both studies compared to the highest floor spaces tested.

Morbidity and mortality levels were also highest in the first study for pigs reared at the lowest floor space treatment. But floor space did not affect morbidity and mortality rates in the second study.

In both studies, pigs raised at the lowest floor spaces had the highest percent lean and least backfat.

Again, both studies suggest that growth rate was maximized at a floor space allowance of 7.3 sq. ft./pig, much lower than published values for the minimum floor space allowance for maximum growth rate.

Researchers: B.A. Peterson, M. Ellis, J.M. DeDecker, M.J. Ritter and C.R. Bertelson, University of Illinois; B.F. Wolter and R. Bowman, The Maschhoffs, Inc.; N. Williams and C. Zeir, PIC USA. Contact Ellis by phone (217) 333-6455, fax (217) 333-7088 or e-mail

Severity of Claw Lesions Analyzed Over a Parity Cycle

A study of a commercial farm in Minnesota revealed that the severity of claw lesions may become more severe over a parity cycle.

In the Pork Checkoff-funded trial, the feet of 98 sows (Parities 1-8) were individually examined between 110-114 days of gestation when the sows were in farrowing stalls.

Lesions consisted of erosions, cracks and overgrowths. Lesions were scored and examined again in their subsequent parity.

Results indicated that the intensity of lesions (front and hind feet) increased over a parity in the lateral (outside) claws and decreased in medial (inside) claws. The intensity of lesions increased in the hind leg lateral claws (toes) in the subsequent parity, whereas front feet lateral claw scores did not differ greatly between parities.

Within the hind leg lateral claws, overgrown heels and intensities of lesions on side walls and white lines increased, while the severity of lesions at heel-sole junction decreased in the next parity.

Within the front leg medial claws, the intensity of white line lesions was reduced in the following parity.

The intensity (irrespective of the orientation of legs and claws) of overgrown heels increased, and intensity of lesions at heel-sole junction decreased in the subsequent parity. The presence of overgrown heels increased, and the presence of lesions at heel-sole junction decreased in the hind feet in the subsequent parity.

The presence of overgrown heels in the front feet was higher in the subsequent parity.

Regardless of the orientation of hooves and legs, the presence of lesions at heel-sole junction decreased, and overgrown heels increased in the subsequent parity.

Results suggest that lesions on hind leg lateral claws may increase in severity over time.

The development of hoof lesions is the result of a complex interaction of floor surface and the horn of the foot. Lesions don't develop equally on all hooves. More lesions have been reported in lateral claws than in medial claws due to greater weight-bearing surface in the lateral claws.

The increase in area of the weight-bearing surface is obviously not corresponding to the increase in weight of the modern breeds that are developed for rapid growth.

As bodyweight increases, the pressure exerted on the hoof area increases the chance of injuries. This may also increase the risk of hoof lesions with the advancement of parity, adding to the number of sows that are culled due to lameness at a younger age than those removed for other reasons.

Researchers: Sukumarannair S. Anil, DVM; Leena Anil, DVM; and John Deen, DVM, University of Minnesota. Contact Sukumarannair S. Anil by phone (612) 625-4243, fax (612)625-1210 or e-mail

Data Suggests Foot, Leg Problems Vary By Packing Plant

A large number of transport losses at slaughter are due to pigs that have difficulty in walking during unloading, commonly referred to as non-ambulatory, non-injured (NANI).

NANI pigs may be part of the cause of dead and fatigued pigs at slaughter, and one possible factor leading to finishing pigs going down during transport to the packing plant.

In trials coordinated at Texas Tech University, data for feet and legs were collected from paired NANI and control pigs at each of four processing plants in the United States (Plants A, B, D and E). There were actually five plants in the overall study, but feet data was unavailable for Plant C.

Plants were located in the lower to upper sections of the Midwest. Plant daily capacity ranged from about 10,000 to 20,000 pigs/day.

The four plants studied comprised 15-20% of annual pig production in the United States.

At the plants, feet and legs of NANI and control pigs were examined for cracked hooves, swollen joints or abscesses. Feet and leg lesion scores were recorded. Score 0 was normal, a score of 1 included minor hoof, pad or joint problems and a score of 2 indicated severe foot or leg problems. All four feet were observed, but the resulting score reflected the worst condition of any foot.

Overall, hoof and foot pad problems were similar for control and NANI pigs, although problems varied by plants (Table 1 on page 27).

NANI pigs had a greater percent of pad problems compared with their control pig counterparts at Plant A.

Total percentage of hoof and pad problems was greater in NANI pigs than in control pigs at Plant E. But the percentage of hoof problems was lower among NANI pigs than control pigs at Plant A, and the number of hoof problems with a score of 2 was lower in NANI pigs than control pigs at Plant B.

Moreover, the percentage of severe hoof and pad problems was greater in NANI pigs than control pigs at Plants A and E.

Conversely, severe foot and pad problems declined more among NANI pigs than control pigs only at Plant B.

In all, more than 50% of pigs surveyed had hoof or pad problems of some kind, and over 30% of these problems were severe.

Results suggest that hoof and pad problems among slaughter weight pigs are a major problem and a welfare concern that deserves attention. These problems represent one of the main causes of NANI pigs that cost the swine industry over $100 million in losses annually.

Researchers: Mhairi Sutherland, Jerry Smith and John McGlone, Texas Tech University. Contact Sutherland by phone (806) 742-2805, ext. 255; fax (806) 742-4003 or e-mail

Temperature, Humidity Can Take a Toll on Market Hogs in Transit

Temperature had opposite effects on the percentage of dead on arrival (DOA) and non-ambulatory, non-injured (NANI) pigs being hauled to market, in a study conducted by Texas Tech University researchers.

The percentage of DOA pigs increased as temperature increased, while the percentage of NANI pigs decreased as temperature increased (Figures 1 and 3).

Prospective data were collected from 16,323 trailers transporting 2,730,754 pigs to a packing plant during a 12-month period.

Pigs that were DOA, NANI and injured on trailer (IOT) were evaluated for the impact of temperature and humidity during transport to slaughter.

In the study, the percentage of DOA pigs increased when temperatures exceeded 68° F. The highest percentage of DOA pigs occurred at temperatures of 77° F and higher.

In contrast, the percentage of NANI pigs decreased as temperature increased above 32° F. The percentage of NANI pigs was 53.4% lower at temperatures of 41° F and above, compared with temperatures below 41° F.

Temperature was not a major factor on the percentage of IOT pigs (Figure 2).

Relative humidity was not a key event for DOA, NANI and IOT pigs in this study.

The increase in DOA pigs as temperature increased may explain the decrease in NANI pigs at high temperatures.

For example, pigs that may have turned into NANI pigs at lower temperatures may not cope at high temperatures (above 68° F) and die, therefore showing up as DOA.

In earlier studies, humidity has not been found to be a cause of DOA. However, regardless of external humidity, the humidity inside a trailer during transport is likely to quickly soar to 100% when the truck stops. This reduces the pig's ability to use evaporative cooling as a means of heat loss. Providing air movement is critical for pigs in trucks that stop for more than a few minutes during warm weather.

The risk of NANI pigs increases in winter, so extra precautions should be taken to prevent market hogs from getting cold during transport and lairage.

Researchers: Mhairi Sutherland and John McGlone, Texas Tech University. Contact Sutherland by phone (806) 742-2805, ext. 255; fax (806) 742-4003, or e-mail

Shorter Holding Time Reduces the Impact of Heat Stress at Slaughter

Market pigs should be kept in lairage less than three hours to improve animal welfare in times of heat stress, according to studies at the University of Missouri.

Researchers evaluated three seasonal environments: temperate (TMP), cold stress (CS) and heat stress (HS); two on-farm handling intensities: conventional (CONV) and passive (PAS); two transport stocking densities: tight (TSD) and loose (LSD); and two holding times at slaughter (lairage): 45 minutes and three hours, and their impact on digestive tract temperature and blood plasmal cortisol levels. Studies were funded by Pork Checkoff.

Market hogs weighing an average of 275 lb. were harvested at TMP (42.8 to 55.4° F), CS (23 to 32°F) and HS (71.6 to 95° F).

At 16 hours prior to slaughter, a computer-activated temperature logging device (Ibutton) was placed down the throat of market hogs. Half the group was randomly subjected to PAS handling and the other half to CONV handling, with each group loaded on trailers with identical dimensions.

Half the pigs loaded were subjected to tight loading (4 sq. ft./pig) and the other half to loose loading density (6 sq. ft./pig). At the plant, half the pigs were allocated to the 45-minute lairage and the other half to the three-hour lairage treatment prior to slaughter. Ibuttons were collected at harvest.

Before handling, CS pigs had higher body temperatures than the other two groups harvested. But during handling, CONV-handled pigs from the HS group displayed no difference in temperature compared to PAS-handled pigs from the CS harvest. Researchers suggested the added activity during CONV handling accelerated the body metabolism of the HS pigs, raising their temperature.

During lairage, pigs from the HS harvest had higher temperatures than pigs from the TMP harvest, which had higher temperatures than CS-harvested pigs. Researchers concluded that the reestablishment of dominance in lairage increased the metabolism of the HS pigs.

Pigs experiencing the three-hour holding time tended to have higher temperatures than pigs kept in lairage for 45 minutes.

Pigs from the HS harvest subjected to TSD had higher cortisol levels than TMP and CS pigs at a TSD, as well as HS and CS pigs at a LSD. This suggested that TSD worsens heat stress.

Pigs from the HS harvest given three hours of lairage had higher cortisol levels than TMP pigs held three hours before slaughter. HS and TMP pigs with three hours of lairage had higher cortisol levels than HS and TMP pigs given 45 minutes of lairage, suggesting that a three-hour lairage exacerbates heat stress.

Researchers: Eric Berg and Chadwick Carr, University of Missouri. Berg took a position at North Dakota State University. Contact Berg by phone (701) 231-6271 or e-mail

Table 1. Feet and Hoof Problem Scores, Percent of the Group, and Gender of Non-Ambulatory, Non-Injured (NANI) and Control Pigs from Four Processing Plants in the United States
Plant A Plant B Plant D Plant E Plant Averages
Measure NANI Control NANI Control NANI Control NANI Control NANI Control
Number of pigs 39 39 36 36 60 60 62 57 197 192
Hoof damage/injury
No. score 1 24.0 33.0 21.0 10.0 21.0 25.0 24.0 21.0 22.5 22.3
No. score 2 3.0 0.0 2.0 11.0* 10.0 10.0 9.0 3.0 6.0 6.0
Total score 27.0 33.0 23.0 21.0 31.0 35.0 33.0 24.0 28.5 28.3
% hoof problems 69.2 84.6* 63.9 58.3 51.7 58.3 53.2 42.1 59.5 60.8
Pad damage/injury
No. score 1 11.0 4.0 20.0 13.0 9.0 14.0 17.0 19.0 14.3 12.5
No. score 2 3.0 0.0 8.0 17.0 25.0 20.0 28.0 14.0 16.0 12.8
Total score 14.0 4.0 28.0 30.0 34.0 34.0 45.0 33.0 30.3 25.3
% pad problems 35.9 10.3* 77.8 83.3 56.7 56.7 72.6 57.9 60.7 52.0
Total feet and leg injuries, % 105.1 94.9 141.7 141.7 108.3 115.0 125.8 100.0* 108.5 105.0
Severe foot problems, % 15.4 0.0* 27.8 77.8* 58.3 50.0 59.7 29.8* 37.5 38.5
*Measures for NANI pigs for each plant and overall differ significantly from controls at P < 0.05.