Factors affecting the incidence of bruising in lambs arriving at one slaughterhouse.
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Abattoirs↗
Biomedical subjects
T G Knowles
Publications and source records attributed to T G Knowles.
Effect of catching method on the concentration of plasma corticosterone in end-of-lay battery hens.
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Animal Husbandry↗
Long distance transport of lambs and the time needed for subsequent recovery.
The effects of nine and 14 hours of road transport and the subsequent recovery in lairage of 392 hill lambs were studied in August and November. The gathering and the handling of the lambs were stressful, both physically and psychologically, and the journey imposed further psychological and metabolic stress. The levels of noise in the trailer were high (90db[A]). There were no measurable differences between the responses of the lambs transported for nine or 14 hours and there appeared to be three stages in their recovery after transport. After the first 24 hours of lairage changes in the blood components usually associated with short term stress and dehydration had recovered; after 96 hours there had been a well defined recovery of liveweight and the levels of most of the metabolites measured appeared to have stabilised and after 144 hours the lambs had recovered almost completely, most of the creatine phosphokinase had been cleared from the plasma and their plasma protein levels had stabilised.
Animals↗
Effect of bone strength on the frequency of broken bones in hens.
Bird weight, breaking strength of humerus and tibiotarsus and the number of bones broken during culling were recorded for four breeds of end-of-lay hens housed in battery cages. The probability of a bone being broken increased with bird weight and decreased with increasing bone strength. Bone strength increased with bird weight within each breed but the increase in strength was not great enough to prevent the extra damage suffered by heavier birds. There were differences in tibiotarsal strength between the four breeds of bird but overall no breed was more likely to suffer from broken bones than another. The rate of increase of bone strength with weight was similar between breeds and between humerus and tibiotarsus. The results show that differences in bone strength due to the type of housing system in which birds are kept are great enough to affect the ease with which bones are broken during bird handling during removal from cages at the end of lay.
Animals↗
Prevalence of leg weakness in broiler chickens and its relationship with genotype.
A method for measuring the prevalence of leg weakness by assessing the walking ability of broilers was developed. Walking ability was divided into six categories, from completely normal to immobile. The method was found to give consistent results when performed by the same people. In a survey of commercial, intensively reared broilers, 90 per cent had a detectable gait abnormality and 26 per cent suffered an abnormality of sufficient severity for their welfare to be considered compromised. The prevalence of leg weakness in free range broilers, and three commercial breeds of broilers was determined. The results indicated that genetic factors were an important cause of leg weakness in broilers and also identified a possible relationship between liveweight and leg weakness.
Animals↗
Influence of width and bends on the ease of movement of pigs along races.
Pigs could be moved along a race 120 cm wide more quickly than along a race 45 cm wide. The presence of a bend with an angle of 45 degrees slowed their progress by about 10 per cent, a bend of 90 degrees or 120 degrees slowed them by 19 per cent and a 180 degrees bend slowed them by 44 per cent. There was little evidence of any interaction between the effects of width and angle of bend; the effect of a sharp bend could not be compensated for by increased width. The pigs became accustomed to the races and moved more quickly in later runs.
Animal Husbandry↗
Effect of the angle of slope on the ease with which pigs negotiate loading ramps.
In experiments to investigate the time taken by pigs to negotiate ramps with different slopes it was found that they ascended with greater facility than they descended. Between 0 degrees and 20 degrees, the slope appeared to have little effect on the time taken to ascend or descend. Above 20 degrees the time taken to ascend increased linearly. The relationship between the time taken to descend and the slope above 20 degrees was biphasic with times increasing substantially above 35 degrees. There were also differences between the times taken on different days but no evidence of habituation. Pigs took longer to climb steeper ramps with wider spaces between cleats but there was no significant effect on the time taken to descend.
Animals↗
Strength of bones in chickens.
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Animals↗
Limb bone strength and movement in laying hens from different housing systems.
Walking and bouts of wing movement performed by 61-week-old ISA brown laying hens which had been taken from one batch of eggs and then kept in three different housing systems which allowed a gradation in spatial freedom, were recorded. After slaughter the breaking strengths of the humerus and tibia of birds from each system were measured. Birds from battery cages exhibited the fewest limb movements and had the weakest bones, their humeri having only 54 per cent of the strength of those of birds from a perchery. Birds from the Elson terrace system were heavier and had a stronger tibia than cage birds. Compared with perchery birds, terrace birds had weaker humeri and also performed fewer wing movements. The results indicate that the amount of movement possible for laying hens in battery cages was insufficient to avoid levels of osteopenia and consequent bone fragility much greater than in birds kept in the perchery and Elson terrace systems.
Animal Feed↗
Variation in behavioural indices of fearfulness and fatigue in transported broilers.
Several behavioural measures were used to determine fearfulness and fatigue in broiler chickens subjected to fasting and/or transportation. There was considerable variability between four replicates, although measures within replicates were acceptably consistent. There was no uniform effect of fasting or transport on behaviour. The most cogent results were obtained by monitoring post-journey behaviour. In the few hours after transport, fasted and transported birds stood more than control birds which could be explained by increased food-searching behaviour and/or arousal. It is argued that the high variability between replicates indicates that considerable efforts must be made to control environmental variables in studies of behaviour after transporting chickens.
Animals↗
The depletion of glycogen stores and indices of dehydration in transported broilers.
Broilers were either not transported or were transported for 2, 4 or 6 hours after having been subjected to food withdrawal times of less than one hour or of ten hours. The birds were then slaughtered using normal commercial practices. The longer period of food deprivation reduced liver weight and glycogen content, and circulating glucose concentrations. It also elevated the ultimate pH value (pHu) in the biceps muscle and by implication, therefore, reduced its glycogen content. With longer journey times, liver weight and glycogen content decreased. Transport had an inconsistent effect on glycogen concentration in the pectoral muscle but progressively reduced its pHu. In contrast, pHu in the biceps progressively increased, by implication because transport depleted muscle glycogen levels. Birds transported further had higher concentrations of total protein in their plasma which, though this was not significant, also had a higher osmolality. This suggests that transported birds became dehydrated. Additionally, the depletion of body glycogen stores might be associated with the perception of fatigue.
Animals↗
Response of broilers to deprivation of food and water for 24 hours.
In order to provide information on the state of hydration of broilers during marketing, 7-week-old Ross broilers of mixed sex were kept at 17 or 23 degrees C and deprived of food, or food and water, for 24 h. Measurements were made of live weight, carcass weight, muscle moisture, packed cell volume, plasma glucose, corticosterone, total protein, osmolality and sodium. There was a decrease in live weight, carcass weight, plasma glucose and plasma total protein, and an increase in packed cell volume and corticosterone, in birds deprived of food, or food and water. Muscle moisture increased in birds deprived of food and decreased in birds deprived of food and water. Osmolality decreased in birds deprived of food, the decrease being greater in birds at 23 degrees C. Plasma sodium levels were higher in birds kept at 23 degrees C and increased only in birds deprived of food and water at 23 degrees C.
Animals↗
New method for objectively assessing lameness in broiler chickens.
A new method for assessing the severity of lameness in broiler chickens is described. The length of time that birds remained standing in shallow water was measured and the results were compared with the results of conventional gait scoring. There was a highly significant (P < 0.001) relationship between the birds' gait scores and their latency to lie down. Over 750 broilers aged between 32 and 45 days of age were tested in commercial houses and whereas nearly all the sound birds were able to stand for at least 15 minutes, the majority of lame birds lay down within five minutes.
Animals↗