Factors influencing the measure of creatinine in non-reproductive pigs

Creatinine (Crea) is generated as a metabolic waste product of muscle metabolism and movement, it is released into plasma and transported to the kidneys where it is filtered and passes into urine. There is little published on the possibility of using Crea as a marker of muscle catabolism in pigs, initial studies (Muller et al. 2015) aimed to determine whether a handheld, portable meter (Nova Biomedical™ StatSensor™ Creatinine and GFR Meter, RHCG, Rosebery, NSW, Australia) could provide an instant measure of Crea that may reflect sow catabolism, rather found Crea to correlate with feed offered across gestation and lactation at two breeder sites. As with all metabolites, daily fluctuations can be caused by many external variates, in the case of Crea, feeding has been suggested as one possible cause of variation. The aim of this study was to investigate the relationship between Crea and feed intake in non-reproductive pigs, which may be useful in group housing systems to identify low intake pigs.

Creatinine levels (whole blood) were assessed in 18-week-old finisher pigs and its correlation to feeding. A total of 64 male finisher pigs were randomly allocated and housed in four pens of 16 pigs with each pen fitted with electronic Feed Intake Recording Equipment (FIRE) which recorded information on individual feed events including individual feed intake and entry and exit time. Individual Crea measurements, a 30 s test using a drop of blood collected from the ear vein and placed directly onto the testing strip of the handheld meter, were taken for three consecutive days at 1300 h, on two separate occasions, 1 week apart. Ambient temperature, at the time of testing, was also recorded. Data were analysed using the Univariate GLM and correlation procedures (Genstat 18, VSN International, Hemel Hempstead, UK).

There were a high number of correlations between the measured variables; however, most significant correlations (P < 0.001) show a weak relationship (Table 1). Crea levels measured were moderately positively correlated with temperature (r = 0.49), which suggests levels of measured Crea may be influenced by the pigs ambient temperature. These results support the findings from prior studies and illustrate the need to consider external stimuli when measuring daily concentrations of Crea using the Nova StatSensor Creatinine Meter.

Table 1.  Relationships and correlations between creatinine and feed intake in pigs