Alistair Lawrence

Food restriction as a cause of stereotypic behaviour in tethered gilts

The behaviour of Large White × Landrace gilts tethered in stalls was studied by scan sampling from 07.00 to 17.00 h on 3 days consecutively every 5 weeks. Results are presented on 30 gilts sampled during their first 5 weeks in the house, period 1, and on 36 gilts during the following 5-week period, period 2. Twenty individuals were common to both samples. Gilts were fed at 08.00 h with a pelleted complete diet, either on low food levels (1·25 to 2·00 kg) or on high food levels (2·2 to 4·0 kg). In both periods behaviour was strongly related to food allowance in individual gilts. Gilts on low food levels spent a greater proportion of their time in the standing position than those on high food levels (period 1, medians 0·31 and 0·12 respectively; period 2, medians 0·27 and 0·11 respectively), spent more time in repetitive behaviour (period 1, medians 0·22 and 0·04 respectively; period 2, medians 0·16 and 0·07 respectively) and spent a greater proportion of their standing time in repetitive behaviour (period 1, medians 0·46 and 0 respectively; period 2, medians 0·30 and 0 respectively). Similarly, all three measures of behaviour correlated negatively with food allowance overall, but there was some indication that food level had a threshold effect, with more activity and repetitive behaviour occurring on food levels below about 2 kg. These results suggest that if food allowances are low tether stalls are not a suitable system of housing for pregnant sows.

Influences of feeding level and physical restriction on development of stereotypies in sows

Abstract In attempting to understand the mechanisms underlying the development of stereotypic behaviour patterns it is important to determine those environmental factors that contribute to the development of such behaviour. The effects of restraint and food restriction on the development of stereotypies in pregnant nulliparous sows, Sus scrofa , were investigated. In the two housing conditions used in the present study, food restriction, but not restraint, was a major factor in increased levels of activity and in particular high levels of drinking and chain manipulation. Food-restricted sows also increased their feeding rate significantly over the experimental period. Restrained sows spent more time in behaviour such as standing inactive and sham chewing that did not involve manipulation or exploration of substrates. Hughes & Duncan (1988, Anim. Behav. , 36 , 1696–1707) proposed that stereotypies result from long-term performance of elements of appetitive behaviour. Their model suggests that, in the present study, stereotypies resulted from both environments preventing the animal proceeding to the consummatory phase of foraging behaviour and ‘switching off’ the underlying motivation. This explanation, however, is not consistent with the observation that time spent in appetitive behaviour did not decrease when the level of stereotypy increased, and that stereotypies were concentrated in the post-feeding period. It is also not consistent with the high levels of drinking and chewing of substrates that the food-restricted sows developed, as these activities appear to be more closely related to consummatory behaviour than to appetitive behaviour. It is concluded that there remain a number of aspects of stereotypies in pigs and other species that cannot be wholly explained by current models.

Naloxone prevents interruption of parturition and increases plasma oxytocin following environmental disturbance in parturient sows

Experiments in rodents have suggested that environmental disturbance can disrupt parturition through an opioid-mediated inhibition of oxytocin secretion. To test this hypothesis in a large animal model, 14 primiparous female pigs were allowed to commence parturition in a strawed pen. Five of these gilts were allowed to continue parturition undisturbed in this pen, while the remainder were moved to a farrowing crate immediately after the birth of the first piglet. At this time, pigs were injected subcutaneously with either the opioid antagonist naloxone (n = 4; dose 1 mg/kg body weight) or saline (n = 5). Whereas the undisturbed pigs all gave birth to a second piglet within 53 min, in three of the five disturbed and saline-treated pigs no further births occurred for 2 h, at which time oxytocin was administered subcutaneously to restart parturition. By contrast, all of the naloxone-treated pigs gave birth spontaneously within 2 h, although mean interbirth intervals were still prolonged compared to undisturbed pigs. In a second experiment, nine primiparous female pigs with chronic catheters preplaced in the external jugular vein were similarly moved after the birth of their first piglet and either injected with naloxone (n = 5) or saline (n = 4). Again, parturition was interrupted in three out of four saline-treated animals for at least 2.5 h, but resumed promptly when exogenous oxytocin was administered. Plasma concentrations of oxytocin in these pigs were significantly lower than in naloxone-treated pigs, five out of six of which gave birth spontaneously to one or more piglets within 2.5 h.(ABSTRACT TRUNCATED AT 250 WORDS)

‘Freedom from hunger’ and preventing obesity: the animal welfare implications of reducing food quantity or quality

In animals, including humans, free access to high-quality (generally energy-dense) food can result in obesity, leading to physiological and health problems. Consequently, various captive animals, including laboratory and companion animals and certain farm animals, are often kept on a restricted diet. Quantitative restriction of food is associated with signs of hunger such as increases in feeding motivation, activity and redirected oral behaviours which may develop into stereotypies. An alternative approach to energy intake restriction is to provide more food, but of a reduced quality. Such alternative diets are usually high in fibre and have lower energy density. The benefits of these alternative diets for animals are controversial: some authors argue that they result in more normal feeding behaviour, promote satiety and so improve animal welfare; others argue that ‘metabolic hunger’ remains no matter how the restriction of energy intake and weight gain is achieved. We discuss the different arguments behind this controversy, focusing on two well-researched cases of food-restricted farmed livestock: pregnant sows and broiler breeders. Disagreement between experts results from differences in assumptions about what determines and controls feeding behaviour and food intake, from the methodology of assessing animal hunger and from the weighting placed on ‘naturalness’ of behaviour as a determinant of welfare. Problems with commonly used behavioural and physiological measures of hunger are discussed. Future research into animal feeding preferences, in particular the relative weight placed on food quantity and quality, would be valuable, alongside more fundamental research into the changes in feeding physiology associated with alternative diets.

Measuring hunger in the pig using operant conditioning: The effect of food restriction

Operant conditioning techniques were used to measure the feeding motivation (hunger) of pigs restricted to the low food levels used under certain commercial conditions. Six Large White × Landrace boars were maintained in individual pens where they received their daily food allowance. Initially food was available ad libitum ; subsequently boars were restricted proportionately to 0·8, 0·6 and 0·4 of their ad libitum intake in a Latin-square design. Finally boars were again offered their previously measured ad libitum intake (treatment 1·0). Hunger was measured by conditioning boars to press a panel 10 times to receive a 7-g reward of food. Operant response rates were measured over 20-min sessions during each of the treatments and at three times of day (pre-feeding, immediately post feeding and 5 h post feeding). Operant response rate was strongly affected by restricting food allowance (means: treatment 1·0, 42 panel presses; 0·8, 212; 0·6, 266; 0·4, 320). There was a signficant interaction between food allowance and time of day ( P P P Restricting pigs to low food levels resulted in a high level of hunger throughout the day. This was so even for food allowances that met current recommended feeding levels sufficient for maintenance and low weight gain (treatment 0·6 equivalent to 1·3 times maintenance). Commercial levels of feeding for the pig breeding population whilst meeting production needs do not satisfy feeding motivation. The hunger resulting from low food levels may act as a major source of stress under certain husbandry conditions such as tether and stall systems for dry sows, where sows are subject to both physical and food restriction.

Ewe–lamb bonding behaviours at birth are affected by maternal undernutrition in pregnancy

Maternal undernutrition in pregnancy results in low birth-weights and impaired postnatal survival in sheep. Largely anecdotal evidence suggests that the expression of appropriate maternal and neonate behaviours may also be disrupted by undernutrition. In the present study, we investigated the effect of a moderate (35 %) reduction in ewe nutritional intake in pregnancy on the expression of ewe-lamb bonding behaviours in primiparous Scottish Blackface ewes. Low-intake (L) ewes had significantly higher plasma progesterone than high-intake (H) ewes from mid-gestation onwards (e.g. plasma progesterone at 20 weeks (ng/ml): H 15.72, L 22.38, sed 1.80, P<0.001), and a lower oestradiol: progesterone value than H ewes at delivery (H 0.46, L 0.35, sed 0.05, P<0.05). Lamb birth-weight was reduced in the L lambs compared with H lambs (mean body weight (kg): H 3.31, L 3.00, sed 0.14, P<0.05), but the incidence of malpresentation at delivery was greater in L lambs. L ewes spent significantly less time licking their lambs than H ewes after delivery (time grooming in 2 h after birth (%): H 56.12, L 48.17, sed 2.639, P<0.01) and were more aggressive towards the lambs. Lamb behaviours were not directly affected by maternal nutritional treatment, but lamb birth-weight had a significant effect on neonatal developmental progress. Low-birth-weight lambs were slower than heavier lambs to stand and sucked less frequently. In tests of maternal attachment to the lamb, H ewes received higher scores than L ewes at both 24 h after birth (ewes receiving high scores (%): H 41.3, L 21.4, P<0.05) and at 3 d postnatal. We conclude that even a moderate level of undernutrition impairs the attachment between ewes and lambs by affecting maternal behaviours expressed at birth. In addition, the results suggest that levels of nutrition resulting in a decrease in birth weight will affect neonatal lamb behavioural progress.

Effect of group size on feeding behaviour, social behaviour, and performance of growing pigs using single-space feeders

Use of computerized feed intake recording (CFIR) equipment allows automatic recording of individual feed intake of animals kept in groups. However, current CFIR systems have only one feeding space per social group which may lead to increased competition for access to the feeder. The present experiment examined the effect of increased competition around a single-space feeder on individual performance and behaviour by manipulating the number of pigs per feeder. 150 male crossbred pigs were penned at 34 ± 0.3 kg (mean ± SE) in groups of 5, 10, 15, or 20 for 29 days with one single-space computerized feeder per pen and 1.06 m2/pig. Pigs kept in groups of 20 made fewer but longer visits to the feeder and ate more and faster than pigs kept in the smaller groups (7.1 vs. 14.3 visits/day, P < 0.01; 6.91 vs. 4.64 min/visit, P < 0.05; 214 vs. 119 g/visit, P < 0.05; 31.6 vs. 25.9 g/min, P < 0.05; means of group size 20 vs. means of group size 5, 10, and 15, respectively). No differences were found between group sizes in daily feed intake, daily live-weight gain and feed conversion ratio (overall means: 1490 g/day, 725 g/ day and 2.09 g/g, respectively). Mean number of aggressive interactions initiated and won were significantly lower for the two largest group sizes on the day of grouping. A rank index based on pairwise aggressive interactions was not correlated to any of the production or feeding behaviour variables. No significant effect of group size was found on mean number of attempts to displace other pigs from the feeder. The change in feeding pattern in the largest groups appears to represent an adaptation to the constraint placed on their feeding behaviour and they succeed in adjusting to the lack of feeding space as there were no significant differences between groups in production variables. A correlation between performance and social behaviour may have been disguised by environmental factors such as space allowance and straw provision or, alternatively, aggression and growth may be independent characteristics.

Provision of straw as a foraging substrate reduces the development of excessive chain and bar manipulation in food restricted sows

Pregnant sows fed at commercial levels remain highly food motivated for most of the day. The inability to express this behaviour appropriately may, under certain conditions, result in the development of abnormal oral activities such as stereotypic chain and bar manipulation. Ninety-six gilts, all between 1 and 3 weeks post service, were entered into a 2X2 factorial design comparing food level (low, 1.8 kg/23 MJ day(-1) (L); high, 3.2 kg/40 MJ day(-1) (H)) and the provision of a foraging substrate (S, straw; N, no straw). The gilts were loose housed in groups of six with individual stalls. A 70 cm chain loop was attached to the front of each stair. The sows were fed at 09:00 h, during which time S sows received straw (approximately 1.5 kg per sow). Behaviour was recorded over the first two parities, by time sampling for the 2 and 6 h after the start of feeding and over 24 h using video recordings. Activity levels were highest just after feeding, with L sows being more active than H sows (L vs. H, 79% vs. 49% for the second hour after the start of feeding, F-1,F-12 = 41.5, P <0.001). Most of the postprandial activity consisted of manipulating substrates. In LN sows, particularly in Parity 2, this behaviour was mainly directed towards chains and bars, resulting in levels three to four times higher than in other groups (26%, 7%, 4% and 4% for the second hour after feeding for LN, LS, HN and HS respectively; Tukeys HSD, P <0.05). LS sows directed their foraging behaviour mainly towards the straw. It is concluded that in food-restricted pregnant sows, abnormally high levels of chain and bar manipulation can be prevented by providing straw which apparently acts as a foraging substrate.

Variability in the expression of maternal behaviour in primiparous sheep: Effects of genotype and litter size

Abstract The effects of ewe genotype and litter size on the expression of maternal behaviour in primiparous sheep were investigated using a lowland breed selected for growth (Suffolk) and a less-selected hill breed of sheep (Scottish Blackface). Focal animal observations were carried out on 58 Blackface (37 singles and 21 twins) and 57 Suffolk ewes (20 singles and 37 twins) during the 2 h after the birth of each lamb. Overall labour was shorter for Blackface ewes compared to Suffolk ewes (62 vs. 84 min, respectively, P P =0.05) and more by single lambs than twins. Although some aspects of negative maternal behaviour were shown by both breeds of primiparous ewe, Suffolk ewes were more likely to abandon a lamb ( P =0.063), and were significantly more likely to be aggressive towards their lamb ( P P P P P P P

Lameness prevalence and risk factors in organic and non-organic dairy herds in the United Kingdom

This study aimed to compare the prevalence of lameness on organic and non-organic dairy farms in the United Kingdom (UK) and to assess which cow and farm factors influenced lameness levels. Forty organic and 40 non-organic dairy farms across the UK were repeatedly visited over a 2.5 year period. On each visit all milking cows were locomotion scored, and information about farm housing, management and husbandry practices was recorded on-farm. Over the whole study, the mean herd lameness prevalence was 16.2%, 16.3% and 19.3% in the autumn, winter and spring observation periods, respectively. Lameness prevalence was lower (P=0.012) on organic farms compared to non-organic farms. Numerous specific factors were found to significantly influence the prevalence of lameness. This study provided evidence that organic management reduced herd lameness. It supported previous research which suggested that lameness is a serious problem on many farms in the UK and further emphasised the multi-factorial aetiology of lameness problems.