Martina Gerken

Effect of water restriction on drinking behaviour and water intake in German black-head mutton sheep and Boer goats

The present study was conducted to evaluate and compare the physiological responses of sheep and goats to water restriction using the deuterium dilution technique (D2O) to predict the total water intake (TWI) in both species. In two consecutive trials, 10 non-lactating Boer goats and 10 non-lactating German black-head mutton ewes were each randomly allocated into a treatment and a control group. In the control groups (n = 5, for each species), water was offered ad libitum, whereas the treatment groups (n = 5, for each species) received water 3 h/day on experimental days 8 to 14 and 6 h every 2 days on experimental days 15 to 22. The respiratory rate, rectal temperature, body mass and drinking behaviour were also recorded. The TWI was estimated by D2O for each animal. Water restriction for 21 h/day or 42 h/2 days had no significant (P > 0.05) effect on water intake (WI), feed intake, WI to dry matter intake ratio or body mass in both species. The absence of differences between species in their WIs was also confirmed using D2O. However, sheep had higher respiratory rates and rectal temperatures than goats in both control and treatment groups. Both species showed the ability to tolerate a moderate water shortage by activating several physiological mechanisms and behavioural strategies.

Deuterium oxide dilution accurately predicts water intake in sheep and goats

The aim of this study was to test whether the deuterium oxide dilution technique accurately predicts water intake in sheep and goats. Two other issues were also studied: (i) a comparison of water intake in sheep and goats and (ii) an assessment of whether observations of drinking behaviour can accurately measure the water intake. In this study, eight dry Boer goats and eight dry German Black Head Mutton ewes were kept under controlled stable conditions. Animals had access to hay and water ad libitum. Diurnal drinking behaviour was recorded by video. Individual daily water intake was measured and estimated for 2 weeks by re-weighing water buckets and from water kinetics using the deuterium oxide dilution technique, respectively. In addition, dry matter intakes were directly measured and were significantly higher in sheep than in goats. The average daily water consumption by drinking differed significantly between the two species, with higher intakes in sheep than in goats. Total body water expressed as a percentage of body mass did not differ between species. Measurement methods of total water intake (TWI) using deuterium oxide dilution and re-weighing water buckets did not differ significantly in both species (P = 0.926). Results obtained for measured and estimated TWI confirm that the isotope dilution technique gives reliable results for estimates of water intake in sheep and goats. The higher amount of water intake in sheep was also reflected by their drinking behaviour. Sheep spent approximately 0.3% per 24-h drinking, while Boer goats spent only 0.1%. However, measured and estimated TWIs were only moderately correlated to the daily time spent drinking. The lower water intake found in Boer goats confirms a superior water management capacity compared with Black Head Mutton sheep even under temperate conditions.

Relationships between integumental characteristics and thermoregulation in South American camelids.

Hair fibre is regarded as a unique mammalian feature with an important role for endothermy. Artificial selection for hair characteristics resulted in marked changes with regard to follicle number, type, distribution, growth and natural shedding. This review focuses on the fine fibre-producing South American camelids (SACs) and the relationship between their hair coat and thermoregulation. SACs have developed several special integumental characteristics. While the hair coat of the wild lamoids vicuña (Vicugna vicugna) and guanaco (Lama guanicoe) is formed by two types of hair (the coarse outer guard hairs and a finer undercoat), the domesticated llamas (Lama glama) and alpaca (Lama pacos) exhibit variably double coat and predominantly single coat, respectively. The distribution of the hair coat across the body is not homogenous. Thermal windows with shorter hair or thinner skin can be identified at the ventral abdomen, axillary space and inside of the thighs (about 20% of the skin), thus allowing to modulate heat dissipation. In contrast to sheep wool, lamoid fibres are mainly medullated. The thermal conductance of summer pelage was higher than that of the winter fleece and highest for the axillar and lower flanks. Lamoids have developed behavioural strategies to modify heat loss by adopting specific postures according to ambient conditions by closing or opening the thermal windows. Energy savings of 67% attributed to posture were calculated. SACs have shown to be able to adapt to a broad range of different climatic conditions. The specific integumental characteristics of SACs indicate that they have developed adaptation mechanisms particularly suited for cooler climates. Accordingly, hyperthermia might become a problem in hot, humid areas outside of their original habitat. Several studies showed the beneficial effect of shearing against heat stress. In particular, fertility in males exposed to heat stress may be improved by shearing. Infrared thermography reveals that in shorn animals the heat is radiated across the entire body surface and is not restricted to the thermal windows. However, shearing also changes the conditions of the protective layer, resulting in a loss of thermal conductance that may result in adverse effects when animals are kept under cold temperatures. The length of residual fibre appears to be crucial in avoiding excessive heat loss in a cold environment, as demonstrated by shearing experiments with different shearing machines. There is, therefore, potential for welfare considerations to conflict with industrial demands for fibre length or homogenous quality.

Short communication: Milk output in llamas (Lama glama) in relation to energy intake and water turnover measured by an isotope dilution technique

Despite the fact that llamas have become increasingly popular as companion and farm animals in both Europe and North America, scientific knowledge on their nutrient requirements is scarce. Compared with other livestock species, relatively little is known especially about the nutrient and energy requirements for lactating llamas. Therefore, we aimed to measure milk output in llama dams using an isotope dilution technique and relate it to energy intakes at different stages of lactation. We also validated the dilution technique by measuring total water turnover (TWT) directly and comparing it with values estimated by the isotope dilution technique. Our study involved 5 lactating llama dams and their suckling young. Milk output and TWT were measured at 4 stages of lactation (wk 3, 10, 18, and 26 postpartum). The method involved the application of the stable hydrogen isotope deuterium ((2)H) to the lactating dam. Drinking water intake and TWT decreased significantly with lactation stage, whether estimated by the isotope dilution technique or calculated from drinking water and water ingested from feeds. In contrast, lactation stage had no effect on dry matter intake, metabolizable energy (ME) intake, or the milk water fraction (i.e., the ratio between milk water excreted and TWT). The ratios between TWT measured and TWT estimated (by isotope dilution) did not differ with lactation stage and were close to 100% in all measurement weeks, indicating that the D(2)O dilution technique estimated TWT with high accuracy and only small variations. Calculating the required ME intakes for lactation from milk output data and gross energy content of milk revealed that, with increasing lactation stage, ME requirements per day for lactation decreased but remained constant per kilogram of milk output. Total measured ME intakes at different stages of lactation were similar to calculated ME intakes from published recommendation models for llamas.

Deuterium for Estimating Total Body Water and Turnover Rates in Turkeys Exposed to Different Incubation Treatments

Total water intake (TWI) in poultry can be influenced by various factors. Recommendations for water requirements are usually reported on a flock basis without considering individual variation. In the present study, a total of 18 turkeys were used to measure water intake over a 1-wk period starting at 15 wk of age by applying the deuterium dilution technique. Poults originated from eggs exposed to different incubation treatments, with eggs incubated at normal temperature (37.5 degrees C) and eggs subjected to 38.5 degrees C at embryonic d 9 to 12. Experimental birds were kept in flocks of 22 to 30 birds separated by sex and treatment. Feed and water were provided ad libitum. Incubation treatment had no significant effect on any of the parameters investigated (BW, daily gain, water turnover rate, total body water, TWI), whereas sex exerted a significant effect on nearly all traits. Total body water ranged between 60 and 65% of BW, with significantly (P < 0.05) greater values for toms (63.2%) than for hens (60.9%). Males had approximately 30% greater water influxes than females (1,054 +/- 198 vs. 742 +/- 153 mL/d, mean +/- SD). However, the significant influence of sex was eliminated (P = 0.464) when TWI was expressed as grams per kilogram of BW (76 +/- 18 vs. 70 +/- 12 mL/kg of BW; males vs. females). Water consumed averaged 837 mL in male and 569 mL per day in female birds. The present results suggest that the isotope dilution method offers a viable method to measure individual water intake, which can be used for establishing reference values for water consumption in group-housed turkeys.

Long-term adaptation capacity of ponies: effect of season and feed restriction on blood and physiological parameters

Domesticated horses are increasingly kept under semi-natural housing conditions, whereas their adaptation capacity is not fully investigated. In all, 10 Shetland pony mares were held under semi-extensive conditions for 1 year. In winter animals were allocated into two feeding groups (60% and 100% of maintenance energy requirement, respectively). Triiodothyronine, thyroxine, non-esterified fatty acids (NEFA), total bilirubin, total protein, triglyceride, glucose, insulin and hair length were measured at monthly intervals, whereas BW, body condition score, cresty neck score and resting heart rate were recorded every 2 weeks. From summer to winter all Ponies showed a reduction in resting heart rate (P0.05). Refeeding of restrictively fed ponies resulted in a rapid increase in resting heart rate and BW and a return of blood parameters to reference values. Adequately supplied animals adapted without difficulty to varying environmental conditions, whereas feed restriction in ponies during winter resulted in reduced resting heart rates suggesting a reduced basal metabolic rate. The energy restriction was compensated by mobilizing body fat reserves which led to changes in blood parameters. Refeeding in feed restricted animals revealed a remarkably quick recovery of physiological and blood parameters to reference values. We therefore suggest that year round-outdoor housing can be a suitable housing system for robust horse breeds provided that an adequate food supply is available.

Individual gregariousness predicts behavioural synchronization in a foraging herbivore, the sheep (Ovis aries).

Diversity of animal personalities has been proposed to arise from differences in social attraction, and to enhance behavioural flexibility of a population. The present study evaluated gregariousness as a personality trait in 14 ewes kept on pasture. Gregariousness was defined based on the frequency of having a close neighbour (<3m). Highly gregarious (HG) and less gregarious (LG) animals were separated into two groups (n=7) which were reintegrated after 18 days. During direct field observations, behaviour was recorded individually every 15 min. Each session lasted 2.5h (08.30-11.00 h or 14.30-17.00 h, respectively). Behavioural synchronization was highest when the group consisted only of HG individuals (κHG=0.69, κLG=0.31; t=5.29; p<0.001), indicating that gregariousness predicted behavioural synchronization in sheep. Though sheep are generally recognized as a highly gregarious species, HG and LG individuals could be differentiated clearly and consistently. Research on animal personality might help explain social influences on behavioural synchronization.

Effect of pasture size on behavioural synchronization and spacing in German Blackface ewes (Ovis aries).

This study aims to assess plot size related changes in spacing and behavioural synchronization in a herd of 14 German Blackface ewes kept on three different pasture sizes: S (126m(2)), M (1100m(2)), and L (11,200m(2)). In direct field observations, behaviour and nearest neighbour distance were recorded individually. Additionally, interindividual and nearest neighbour distances were derived from aerial photographs of the herd taken on plot sizes S and M. Nearest neighbour distances <1m accounted for more than 60% of observations, and were more frequent on plot size L than on plot sizes S (Z=3.3; p<0.01) and M (Z=3.2; p<0.01). Average interindividual distances were significantly smaller on S (4.89±2.62m) than on M plots (5.99±3.06m; t=7.3; p<0.01). Synchronization tended to increase with plot size (K(S)=0.42; K(M)=0.52; K(L)=0.66), but was not accompanied by a concomitant increase in dispersion. Aerial photography proved a valuable tool in the analysis of spacing behaviour as intraindividual repeatability of the derived distances was highly significant (Kendalls W between 0.32 and 0.58; p<0.01). The sheep kept small distances on all plot sizes, thus the high degree of behavioural synchronization might be mainly attributed to the motivation for close proximity to any conspecific.

Lactation in llamas (Lama glama): estimating milk intake and output using stable isotope techniques

Compared to many other domesticated ruminants, very little is known about lactation in South American camelids. However, knowledge about milk and milk nutrient intakes in suckling young is essential for giving recommendations on an adequate nutrient supply. Direct measurement of milk production in South American camelids is hardly applicable, due to their short teats of about 2 cm and the low storage capacity of the udder. Therefore, we estimated milk production in llamas by measuring the milk intake in suckling young as an indirect trait. The study was conducted in Germany under temperate climatic conditions involving 11 lactating dams at two consecutive lactation periods (average body mass: 147.7±18.2, mean ± SD). Milk intake was estimated from water kinetics of 17 suckling young using two different stable isotope techniques, namely the isotope dilution technique involving the application of deuterium oxide (D2O) to the suckling young and the ’dose-to-the-mother’ technique involving the application of D2O to the lactating dam. The latter method additionally allows for the estimation of non-milk water intakes of suckling young. Daily milk intakes averaged 2.7±0.63, 2.2±0.60 and 2.0 ± 0.51 kg at 3-4, 10-11 and 18-19 weeks postpartum. Milk intake in suckling young decreased with age when expressed as daily amount, percentage of body mass or per kg metabolic size (P < 0.001), but the influence of age was eliminated when expressed per g daily gain. In suckling llamas, total water turnover increased with age (P < 0.01), whereas the milk water fraction decreased (P < 0.001). With increasing age less water from milk and more water from other sources was ingested. In contrast, the fraction of the milk water excreted by the dam did not change, indicating a fairly constant relationship between milk-water excreted via milk and total water ingested during lactation. Our results show that the stable isotope techniques used in the present study give reasonable estimates of the milk production in llamas. Furthermore, combined with milk composition data, the present milk intake estimations at different stages of lactation can be used to establish recommendations for nutrient and energy requirements of suckling llamas and lactating dams.