By K.E. Lannom and W.L. Flowers, North Carolina State University Department of Animal Science
In order to increase their chances of being weaned, newborn piglets need to first consume adequate amounts of colostrum and then milk. This has been well-documented in numerous studies and is one of the primary reasons there has been renewed interest in the implementation of early critical care programs in farrowing barns.
A number of different factors affect production of colostrum and mature milk with one of these being the anatomical location of the teat. The general assumption that has been made is that the quality of colostrum and milk decreases as the anatomical location becomes more posterior. A comprehensive quantitative assessment of these perceived anatomical differences in colostrum and milk and their associated effects on piglet growth and survival were evaluated in a modern genetic line of sows that averaged 13.8 + 0.2 and 11.8 + 0.3, piglet born alive and weaned, respectively.
Composition of colostrum and milk and nursing activity, growth and survival of piglets were monitored in 45 sows between Parities 2 and 4 for three consecutive lactations. Colostrum samples were collected just prior to or just after the birth of the first piglet and milk samples were collected on Day 14 of lactation. Piglets were identified by placing different colored marks on their backs and their nursing activity was observed on Days 1, 3, 7, 14 and 21 of lactation. Individual piglet weights were collected at birth and then every seven days.
All sows began lactation with at least 12 piglets and had at least 14 functional nipples as determined by the presence of colostrum. Results from the study are shown in Tables 1, 2 and 3. All data were averaged across both teats in each pair and data from piglets that nursed the last (eighth) pair of teats were pooled with data from those that nursed the seventh pair.
In general, it did appear that piglets nursing the anterior teats had heavier weaning weights and better survival than piglets nursing the posterior ones. A portion of these differences could be due to the birth weight of the piglets since there was a tendency for the heavier piglets to nurse the anterior teats compared with their lighter litter mates. However, the average birth weight for piglets that nursed the seventh (and eighth) pair of teats was still above 3 pounds so these would not be considered runt or underdeveloped piglets.
The majority of the effect of teat location on piglet growth and survival probably was related to the quality of colostrum and milk as well as the nursing activity of the piglets, themselves. The protein content of colostrum and the fat content of mature milk both decreased as the position of the teat became more posterior.
In addition, piglets that began nursing the first two pairs of teats tended to nurse these during the entire suckling bout compared with piglets that began nursing teats located in the posterior positions of the underline. In other words, once piglets started nursing one of the first two pairs they stayed on them and didn’t switch whereas piglets that began nursing the posterior ones were more likely to change and nurse several teats during a single nursing bout.
Even though these data are purely descriptive, they do have implications with regards to lactation management for piglets. Piglets that nursed the last three pairs had reduced growth and survivability than those that nursed the first three pairs of pairs. Consequently, during cross-fostering, adjusting numbers of piglets so there are several pairs of posterior teats for piglets to nurse instead of a single pair could provide them with additional opportunities for colostrum and milk since they tended to switch the teat they were nursing frequently. This could be viewed as a way to give them the opportunity to obtain increased amounts of milk. In terms of split-suckling and partial weaning, removal of piglets nursing the first two pairs of teats seems like a prudent approach since these teats have higher quality milk and piglets nursing the posterior ones, based on their tendency to nurse several teats during a single suckling bout, appear to be more likely to readily begin to nurse these if they were vacant.
Obviously, these are just speculations which require further investigation to determine their effectiveness.