Characteristics of Piglets Born by Two Highly Prolific Sow Hybrids

Abstract

High piglet mortality constitutes a welfare challenge in Danish organic pig production with almost one in three piglets dying before weaning. Piglet characteristics such as birth weight, rectal temperature and intrauterine growth restriction (IUGR) affect piglet survival. Due to differences in breeding goals, these characteristics may be expected to differ between sow hybrids. Thus, the aims of the present study were (1) to investigate piglet characteristics in two highly prolific sow hybrids and (2) to study to which extent the aforementioned characteristics affect piglet mortality. Forty-nine sows (22 DanBred and 27 Topigs Norsvin) were followed in their first two parities. Sows were housed outdoors and gave birth in huts. On day 1 postpartum ( pp ) piglets were individually marked, weighed, their rectal temperature was recorded and they were scored for IUGR. Weight and rectal temperature were recorded again 3 days pp. Principal component analyses were conducted to explore relationships among variables. Early piglet death grouped with IUGR, lower rectal temperature and weight on day 1 pp. Late mortality grouped with increasing litter size and DanBred hybrid. Whilst, Topigs Norsvin hybrid grouped with increasing rectal temperature day 3 pp, longer crown to rump length, higher weight and more teats on the sow. Results of the statistical analyses showed that Topigs Norsvin piglets were heavier 1 and 3 days pp (p < 0.001) compared to DanBred piglets. Furthermore, Topigs Norsvin piglets had a higher rectal temperature than DanBred on day 1 pp (p = 0.023). The risk of IUGR depended on an interaction between sow hybrid and parity (p = 0.023). DanBred sows gave birth to more piglets (18.2 ± 0.6) than Topigs Norsvin sows (15.7 ± 0.5, p = 0.003), however, DanBred sows had fewer teats than Topigs Norsvin sows. Weight on day 1 pp affected both the odds of stillbirth (p < 0.001) and live born death (p < 0.001). Lower rectal temperature day 1 pp (p < 0.001) increased the odds of live born death. In conclusion, the investigated hybrids differed in several piglet characteristics related to piglet mortality. Use of sows giving birth to heavier and fewer piglets in the litter may thus be a useful tool to reduce piglet mortality in pig production with outdoor farrowing.

Keywords: animal welfare; lactating sows; organic pig production; outdoor farrowing; piglet mortality; piglet viability; sow genetics; sow parity.

Figure 1

PCA of the relation in the two first dimensions between the recorded variables including both stillborn and live born piglets. Litter size refers to the number of total born piglets in the litter (incl. stillborn), cross fostering refers to whether piglets were cross fostered, second parity to whether the sow gave birth in her second parity (opposite were sows giving birth in first parity), protein low to whether sows received a low protein level in her diet (opposed to normal protein level), male to whether the piglet born was male (opposed to female), stillborn to whether the piglet was stillborn, IUGR to whether the piglet displayed signs of intrauterine growth restriction (opposed to not), Ahut to whether the piglet was born in an A-frame hut (as opposed to a communal hut), CTR to the crown to rump length of the piglet, teat number to the number of teats on the sow, TN70 to whether the piglet was born to a Topigs Norsvin TN70 sow (as opposed to a DanBred sow), and lastly weightD1 to piglet weight recorded on day 1 postpartum.

Figure 2

PCA of the relation in the two first dimensions between the recorded variables including live born piglets surviving till at least day 1 pp. Litter size refers to the number of total born piglets in the litter (incl. stillborn), cross fostering refers to whether piglets were cross fostered, second parity to whether the sow gave birth in her second parity (opposite were sows giving birth in first parity), protein low to whether sows received a low protein level in her diet (opposed to normal protein level), male to whether the piglet born was male (opposed to female), DeadPreD3 to whether the piglet died before 3 days postpartum (pp), IUGR to whether the piglet displayed signs of intrauterine growth restriction (opposed to not), Ahut to whether the piglet was born in an A-frame hut (as opposed to a communal hut), CTR to the crown to rump length of the piglet, teat number to the number of teats on the sow, TN70 to whether the piglet was born to a Topigs Norsvin TN70 sow (as opposed to a DanBred sow), weightD1 to piglet weight recorded on day 1 pp, and RecTempD1 to the rectal temperature of the piglet recorded on day 1 pp.

Figure 3

PCA of the relation in the two first dimensions between the recorded variables including live born piglets surviving till at least day 3 pp. Litter size refers to the number of total born piglets in the litter (incl. stillborn), cross fostering refers to whether piglets were cross fostered, second parity to whether the sow gave birth in her second parity (opposite were sows giving birth in first parity), protein low to whether sows received a low protein level in her diet (opposed to normal protein level), male to whether the piglet born was male (opposed to female), DeadPreWean to whether the piglet died before weaning (in week 6 postpartum (pp) or earlier), IUGR to whether the piglet displayed signs of intrauterine growth restriction (opposed to not), Ahut to whether the piglet was born in an A-frame hut (as opposed to a communal hut), CTR to the crown to rump length of the piglet, teat number to the number of teats on the sow, TN70 to whether the piglet was born to a Topigs Norsvin TN70 sow (as opposed to a DanBred sow), weightD1 to piglet weight recorded on day 1 pp, weightD3 to piglet weight recorded on day 3 pp, RecTempD1 to the rectal temperature of the piglet recorded on day 1 pp, and RecTempD3 to the rectal temperature of the piglet recorded on day 3 pp.

Figure 4

The proportion of piglets in different birth weight intervals of two hybrids [DanBred and TN70 (Topigs Norsvin)] in first and second parity.

Figure 5

The odds of being an IUGR piglet in two hybrids [DanBred and TN70 (Topigs Norsvin)] for first and second parity. Results are shown with 95% confidence interval bars.