Increased litter sizes in recent years have put a strain on preweaning survivability. One of the main causes is the piglets' inability to regulate body temperature soon after birth.

Does heat lamp and piglet placement in the farrowing crate have an impact on piglet survivability to weaning? That's the question Purdue University Survivability Undergraduate Interns Alicia Denton and Alton Holstine sought to answer in a recent research project.

The study conducted between March and July 2021 included 1,053 piglets from 87 litters farrowing and was a 2 x 2 factorial examining the placement of the heat lamp throughout the farrowing process, and where the piglet was located in the farrowing crate. Sows were blocked by parity and assigned to one of four treatments:

Treatment 1:  Heat lamp and piglet both placed at the sow's udder side (HLU/PU).
Treatment 2:  Heat lamp placed at the back of the sow while piglet placed at the udder (HLB/PU).
Treatment 3: Heat lamp placed at the udder while piglet was placed at the vulva (HLU/PV).
Treatment 4:  Heat lamp placed at the back of the sow while piglet was placed at the vulva (HLB/PV).

At birth, the students collected each piglet's body weight as well as the rectal temperature and then assessed each piglet on the level of meconium staining and their umbilical cord integrity.

They also identified each piglet with a number on its back. Piglets were not completely dried off at birth, only a small portion of their backs, using a paper towel to label them with a number. 

Rectal temperatures were collected at 30 minutes, one hour, two hours and 24 hours after birth. Body weight was taken at 24 hours after birth as well as weekly throughout the lactation. The students also recorded mortality as well as the reasoning throughout lactation.

SAS v9.4 software was used to evaluate the effects of heat lamp location and piglet placement on piglet colostrum intake, growth and survival. Additional evaluations looked at whether piglets with birth weights of more than 1.0 kilograms, 1.0-1.5kg, or more than 1.5kg responded to treatments differently.

Holstine notes, when all four treatments were evaluated together, there was a tendency for rectal temperature in HLU/PV piglets to be lower 30 minutes after birth (P=0.097) however, no additional differences were observed beyond that. The researchers say this effect was driven by the piglet placement more than the heat lamp location as piglets placed at the vulva had lower body temperature at 30 minutes after birth compared to those placed at the udder, regardless of heat lamp location (P=0.0192).

Piglets that were placed at the udder approached the udder faster (P<0.001) and suckled sooner (P=0.0186) compared to piglets that were placed at the vulva, regardless of heat lamp location. However, this did not result in increased colostrum intake (P=0.6581), average daily gain throughout lactation (P=0.2359) or piglet survival (P=0.1581).

"Overall placing newborn piglets at the udder increased the body temperature at 30 minutes after birth and decreased the time to first suckle regardless of location of the heat lamp," Denton says.

Finally, the researchers note that the piglets born ≤1.0kg had higher mortality (39%) than heavier pigs (7-12%, P<0.0001), but neither heat lamp placement nor piglet placement improved survival or ADG in the lightweight piglets. Piglet body weight was the largest driver of colostrum intake, nursing behaviors and survival to weaning.