The study presented by B.L. Buzzard of Kansas State University and co-authors there and at Colorado State University examined the effects of restraint and blood sampling method on blood lactate concentration (LAC) in pigs.

Restraint methods used were snaring or restraint with sorting boards. Blood was sampled from 120 pigs at approximately 165 days of age (278.0±6.4lb) over two consecutive days. Each day, 30 pigs were sampled per method. All pigs were housed in one barn, and pigs in adjacent pens were not sampled simultaneously.

Snaring consisted of a trained handler snaring each pig while blood was collected via jugular venipuncture (approximately 7mL). Restraint with sorting boards consisted of a trained handler restraining each pig with two sorting boards and the side of the pen to form a three-sided barrier to reduce pig movement. The distal ear vein was pricked with a 20-gauge needle to obtain several drops of blood for LAC analysis. Lactate concentration was measured using a hand-held lactate analyser.

The duration of restraint and a behaviour score (1 to 4; 1=no vocalisation or movement and 4=constant movement, vocalisation and struggle) for each pig were recorded during sampling. Blood lactate was compared between the two sampling methods and duration of restraint was used as a covariate in the analysis.

Results indicated that snared pigs had greater (P=0.04) LAC than pigs restrained using the sorting board method, 2.4±0.1 and 2.1±0.1mM, respectively. Both measurements of LAC were considerably lower than the baseline LAC reported in published literature.

A positive correlation (r=0.42, P=0.001) was observed between duration and LAC for pigs that were restrained by snaring; the longer the restraint duration, the greater the LAC. Positive correlations were observed between duration and behaviour score (r=0.41, P=0.001), duration and LAC (r=0.64, P=0.001) and behaviour score and LAC (r=0.26, P=0.05) in pigs restrained with sorting boards.

In the boarded group, longer durations and higher behaviour scores were related to increased LAC.

In addition to analysing behaviour, duration of restraint and LAC, different methods of blood analysis were measured to determine whether the analysis method affected LAC.

Samples for this trial were collected from exsanguination blood from a separate set of 56 market-weight pigs to the same specifications as restraint blood samples. Both serum and plasma were analysed using three methods — YSI analyzer, hand-held lactate analyser and ELISA plate reader — to compare the differences in LAC.

Results showed significant variation in values obtained from the three different methods of analysis (P=0.001). Additionally, values obtained from serum differed significantly from values obtained from plasma (P<0.001).

When comparing LAC values across studies, attention should be given to the medium of measurement and the method of analysis to make reliable comparisons, concluded Buzzard and co-authors.

Reference

Buzzard B.L., L.N. Edwards-Callaway, R.D. Goodband, D.B. Anderson T.E. Engle and and T. Grandin. 2012. Comparison of pig restraint, sampling methods, and analysis on blood lactate concentration. Proceedings of the Kansas State University Swine Industry Day 2012, p409-414.

Further Reading You can view the full paper in the proceedings by clicking here. Other papers presented at this conference can be viewed by clicking here.

February 2013