Determination of new hematologic reference intervals for sows with optimal reproductive performance, according to reproductive stage, parity and body condition: A cohort study

Abstract

Background. Inappropriate feeding and reproductive management according to strategies in sow's reproductive efficiency produce important consequences on sow metabolism. The metabolic alterations can increase mortality and reduce fertility, productivity and lifespan of sows within a farm, decreasing herd output. In according to that, this research aimed to determine the effect of reproductive stage, parity and body condition on hematological parameters of intensive-production sows and also to establish new and representative hematological Reference Intervals for each stage of the reproductive cycle in Chilean sows of optimal reproductive performance. In order to that, a cohort study in 307 healthy sows from two farms was performed. Serial hemograms were obtained and sows were monitored at weaning, prior to artificial insemination, at 35, 60 and 90 days of gestation, and subsequent weaning. Results were analyzed by Repeated-Measures of Anova and Tukey Test to establish differences between times and by the Kruskall-Wallis Test, or Simple Anova Test, to determine differences within times caused by the body condition (BC) or sow age. Results: Significant differences were found in most factors during gestation (P=0,00). At each time frame considered, there was an effect of parity. The sow`s parity history, their BC and the farm`s infrastructure and environment were all relevant factors in each hematological parameter. Additionally, statistically significant differences in almost all the evaluated indicators were contrasted with reference IRs (P=0,00). Hematological indicators supported the interaction between BC and parity in some sows. ConclusionsThis study showed the need of not only specific reference intervals for high-production sows, but also highlights the relevance of considering the different stages of sows´s reproductive cycle. Consideration of sow’s physiological stage and parity, along with body condition appear to be highly relevant to get appropriate hematologic reference intervals.