Agriculture Reference
In-Depth Information
1. Conditioning of the gilt for optimal
reproductive performance
D.W. Rozeboom
Department of Animal Science, Michigan State University, 474 S. Shaw Lane, 2209
Anthony Hall, East Lansing, MI 48824, USA;
rozeboom@msu.edu
Abstract
Gilt development is essential for sustaining a productive herd. Limits or targets of body
condition at the beginning of first pregnancy are thought important and are frequently
described in recommendations about how to ensure long and successful reproductive
lifetime. Evidence suggests that backfat depth at first service is poorly related to life time
productivity. Alternatively, a weight range of 135 to 150 kg at first service has broad
recognition as a credible indicator of physiological preparedness and is an effective target
in gilt pool management protocols. Although suspected to be most vital, less is known
about the relationship between body protein mass or accretion rate and reproduction.
Challenges exist with efforts to better understand the importance of conditioning the gilt
for reproductive performance.
Keywords:
female, swine, development, lifetime reproduction
1.1
Introduction
Conditioning of the gilt for optimal reproductive performance may be better stated as
conditioning of the gilt for maximal lifetime reproductive performance and economic
efficiency. These two statements have different meanings. The second is more explicit
about getting the most pigs in the least time and least financial cost, whereas in the first
statement, the word 'optimal' is subjective, and it is not clear if it suggests a need for
economic sustainability. There seems to be an agreement that, to some unknown degree,
the 'conditioning' of gilts during their development influences their lifetime reproduction
measured as the greatest numbers of pigs and fewest non-productive female days before,
between, and after reproductive cycles. The goal is therefore efficient output and the
following question then arises: Can intentionally and specifically conditioning the gilt
bring about the maximum number of pigs weaned per litter and the fewest opportunities
to fail to stay in the herd? The near-perfect situation for the sow herd would be replacing
30% of females annually, after completing 8 parities and weaning 88 piglets.
Condition of gilts is a description or assessment of body mass or composition. It is
an observed assessment of amounts of various tissues (fat, muscle, teeth, bone and
connective, nervous) and contents (blood, lymph, digesta, urine and gases). Practically
in relation to gilt development, body condition mostly refers to amounts of fat, protein
and skeleton. Rate of growth is also often included in discussions on body condition.
