Researchers: Mike Ellis, Naomi Cooper and Katherine Vande Pol, University of Illinois Department of Animal Sciences; Richard Gates and Yijie Xiong, University of Illinois Department of Agricultural and Biological Engineering
Pre-weaning mortality in U.S. commercial swine herds currently averages around 15% of piglets born alive, representing both a substantial economic loss and a major welfare concern. Two predisposing factors for mortality are low birth weights and reduced body temperature in the early post-natal period. All piglets will experience a decline in body temperature immediately after birth, and this decline is likely to be greater in lighter piglets.
However, there is little published information on post-natal changes in piglet body temperature. This preliminary study was carried out to quantify changes in and the effect of birth weight on piglet body temperature in the first 24 hours after birth under typical farrowing house conditions.
The study was carried out in the farrowing facility at the University of Illinois Swine Research Center, which consisted of typical farrowing pens consisting of a sow crate and surrounding area (total floor space 38 square feet) with a heat lamp on one side. The farrowing room thermostat was set at 73.0 degree F. A total of 350 piglets from 34 litters (172 barrows and 178 gilts) were involved with the parity of the sows ranging from 1 to 6. Piglet rectal temperature was measured at birth, and at 15, 30, 45, 60, 90, 120, 180 and 240 minutes, and 24 hours after birth. Piglet birth weights were collected immediately after birth. For analysis, temperature data were divided into four birth weight groups (Group 1: ≤ 2.00 pounds; Group 2: 2.01 to 3.09 pounds; Group 3: 3.10 to 4.14 pounds; and Group 4: ≥ 4.14 pounds)
Average piglet weight and rectal temperature at birth were 3.03 ± 0.761 pounds and 102.2 ± 1.64 degrees F, respectively. Changes in the average piglet rectal temperature at the times of measurement in the first 24 hours after birth are illustrated in Figure 1. Temperatures declined immediately after birth with the largest decrease being observed at 30 minutes after birth (-8.3 ± 3.16 degrees F). Subsequently, temperatures increased gradually but were on average still below the birth temperature at four and 24 hours after birth (-1.65 ± 2.17 degree F and -1.01 ± 1.91 degrees F, respectively).
One of the most striking findings of this research is the very large range between the lowest and highest temperatures for individual piglets which were observed at all times of measurement from birth onwards (Figure 1). At birth, this range was approximately 9 degrees F and increased to a maximum of 28 degrees F at 90 minutes after birth. This highlights that changes in body temperature in the early post-natal period vary dramatically between individual piglets.
The impact of birth weight group on changes in piglet rectal temperature is shown in Figure 2.
At birth, the rectal temperatures were similar for the four birth weight groups. However, subsequently the lightest group had lower rectal temperatures than the others for the other measurement times. The greatest difference in rectal temperature between the lightest and heaviest groups (4.8 degrees F) was at 30 minutes after birth. Interestingly, the lightest group still had a lower rectal temperature than the heaviest group at 24 hours after birth (1.8 degrees F).
These results highlight that all piglets experience a decrease in body temperature immediately after birth and, although temperatures subsequently increase they still had not returned to the original birth temperature even at 24 hours after birth. In addition, there was considerable variation between individual piglets in the extent of this decline with the lightest pigs (i.e., ≤ 2.00 pound birth weight) showing the greatest decrease and slowest recovery. Further research is needed to investigate approaches to minimizing post-natal temperature decline, particularly for low birth weight piglets.
For more information, contact Mike Ellis.