Measure and characterization of lameness in gestating sows using force plate, kinematic, and accelerometer methods.

The objective was to assess sows' lameness by measuring weight distribution on limbs using a force plate made up of 4 individual platforms each resting on 4 single-ended beam load cells. The weight was recorded at an average rate of 14 readings per s over a 15 min period. Ten sows (5 lame sows and 5 sound sows) were weighed twice on 2 different days to assess the repeatability of the measure. Sixty-one sows were then selected in 2 different sites and visually scored for lameness, using a 3-point scoring system (0=normal gait; 1=abnormal gait, and/or stiffness; and 2=shortened stride, and/or the sow puts less weight or avoids putting weight on 1 leg). Various measures were recorded from each sow using the force plate (percentage of weight, the ratio between the weights applied by contralateral legs, weight shifting, and amplitude of weight bearing and weight removing), kinematics (speed, stride length, swing time, stance time, foot height, and carpal and tarsal joints angle average and amplitude), and accelerometers (time spent standing during 24 h, frequency of stepping behavior during feeding, and latency to lie down after feed delivery). The within-sow CV for each measure taken from the force plate were lower than 15%, which reflects a good repeatability. Among force plate measures, only the weight shifting frequency and the ratio between the weights applied by contralateral legs differed between lameness scores. Sows that scored 2 had a higher frequency of weight shifting for fore legs (P=0.0003) and hind legs (P=0.0007) than sows scored 0 and 1. The ratio between the weights applied by contralateral legs decreased with the increase of lameness score for the hind limbs (P=0.014). However, these measures also differed between sites (P<0.01). These differences may be due to various reasons, including but not limited to genetics and housing systems. Nevertheless, the results suggest that force plate measures such as the asymmetry in the weight applied between a pair of legs and weight shifting are good indicators of lameness. Multivariate analysis on fore and hind legs showed independency between variables related to animals in movement (measures from kinematics) and variables related to static animals (measures from the force plate and accelerometers). Therefore, both static and dynamic methods need to be used to detect various lame sows.

Dairy cow feeding space requirements assessed in a Y-maze choice test.

The effect of proximity to a dominant cow on a low-ranking cow's willingness to feed was assessed using choice tests. The main aim of the experiment was to determine the feeding space allowance at which the majority of subordinate cows would choose to feed on high-palatability food (HPF) next to a dominant cow rather than feeding alone on low-palatability food (LPF). Thirty Holstein-Friesian cows were used in the study. Half of the cows were trained to make an association between a black bin and HPF and a white bin and LPF, and the other half were trained with the opposite combination. Observations of pair-wise aggressive interactions were observed during feeding to determine the relative social status of each cow. From this, dominant and subordinate cows were allocated to experimental pairs. When cows had achieved an HPF preference with an 80% success rate in training, they were presented with choices using a Y-maze test apparatus, in which cows were offered choices between feeding on HPF with a dominant cow and feeding on LPF alone. Four different space allowances were tested at the HPF feeder: 0.3, 0.45, 0.6, and 0.75 m. At the 2 smaller space allowances, cows preferred to feed alone (choices between feeding alone or not for 0.3- and 0.45-m tests were significantly different). For the 2 larger space allowances, cows had no significant preferences (number of choices for feeding alone or with a dominant). Given that low-status cows are willing to sacrifice food quality to avoid close contact with a dominant animal, we suggest that the feeding space allowance should be at least 0.6m per cow whenever possible. However, even when space allowances are large, it is clear that some subordinate cows will still prefer to avoid proximity to dominant individuals.