Effect of floor type on hoof lesions, dirt scores, immune response and production of beef bulls

• Greater ADG and carcass gain for bulls on rubber mats compared with concrete slats.
• Floor type had no effect on dry matter intake, slaughter weight or carcass weight.
• Bulls on rubber mats had more hoof lesions compared with those on concrete slats.
• Floor type had no effect on dirt score.
• Floor type had no effect on any of the haematology variables measured.

The objective of the study was to investigate the effect of old and new concrete slats (CS) with or without rubber mats (RM) on animal performance, hoof health, dirt scores and health status of finishing bulls. Continental crossbred beef bulls (n=72; mean initial live weight=441 (s.d. 45.1) kg) were blocked by breed and live weight and randomly assigned by block to one of four treatments; (1) Old CS (2) New CS, (3) Old CS covered with RM, (4) New CS covered with RM. Each treatment had 3 pens of 6 bulls at a space allowance of 2.9 m2 per animal. Bulls were fed a total mixed ration (TMR) of silage and rolled barley on a 54:46 dry matter (DM) basis for 148 days. Feed was weighed into each pen daily and refusals were weighed twice weekly. Bulls were weighed every three weeks to coincide with dirt scoring. Total leucocyte, neutrophil, lymphocyte, eosinophil, monocyte, basophil and red blood cell number and haemoglobin concentrations were measured on day 0 and day 148. Bull's hooves were inspected for the presence of lesions at the start of the study and again at slaughter. After slaughter, carcass weight, carcass gain, conformation and fat score, kidney and channel fat and hide weight were recorded. Bulls on RM had a greater average daily gain (ADG) (0.16 kg/day) (P<0.01), kidney and channel fat weight (KCF) (P<0.05), hide weight (P<0.01) and a better feed conversion ratio (FCR) (P<0.05) than those on CS. Floor type had no effect on dry matter intake (DMI), slaughter weight, carcass weight, kill out percentage, conformation score or fat score. Bulls on RM had 44% more hoof lesions (P<0.01) than those on CS. There were slat×time (P<0.05) and mat×time (P<0.01) interactions for dirt scores. Bulls on slats were dirtier than those on mats on days 63, 84 and 126 (P<0.01) while bulls on new slats were dirtier than those on old slats on days 21 (P<0.01) and 42 (P<0.05). Floor type had no effect (P>0.05) on any of the haematological variables measured which suggests that the immunological status of the bulls was not affected by treatment. While there was no evidence of lameness in bulls on RM, the increased number of hoof lesions suggests that hoof health may be compromised in bulls housed on RM.