The reaction of cows to a short-term deprivation of lying

In a herd of 20 cows in a cubicle house, lying behaviour was prevented for 3 h each morning by enclosing the animals on the slatted floor of the feeding area. Lying time of cows was recorded during the 10 h following deprivation. The 3 h of lying deprivation resulted in a recovery rate of almost 50% within the observation period. When cows were also deprived of food during the lying-deprivation period, the recovery rate of lying did not alter. However, when feeding alone was prevented, the increased feeding tendency did decrease lying time in the subsequent hour. It is concluded that cows aim to achieve a rather fixed amount of lying, and that their well-being must seriously be impaired when lying time is restricted for several hours.     

Behaviour of dairy cows when fed concentrates with an automatic feeding system

On Dutch commercial farms automatic systems for feeding concentrates in a feeding station are being used increasingly. Various systems have been developed, which differ in the timing and amount of concentrates made available to the cows over a 24-h period. Three types of a fixed-time system and one variable-time system are compared with a traditional system. The fixed-time systems provided a ration of concentrates every 12 h. The starting time of these 12-h cycles varied, hence the fixed-7-time system started at 07:00 and 19:00 h; the fixed-11-time system cycles started at 11:00 and 23:00 h; and the fixed-3-time system cycles started at 15:00 and 03:00 h. The variable-time system continuously added small amounts of concentrates to the available ration per cow throughout a 24-h cycle. The traditional system provided concentrates mixed with maize silage at the feeding rack. The aim of the investigation was to describe the pattern of intake of concentrates, and the possible consequences of the various feeding systems on the cows' general activities such as eating, standing and lying down.

Three experiments were carried out, each with a group of 20 lactating dairy cows kept in a cubicle house with a single concentrates feeding station. In each of the experiments, feeding systems were tested during 3-week experimental periods. Behaviour was observed during three 24-h periods in each experimental period.

It was found that each of the five feeding systems tested evoked a typical pattern of visits to the feeding station. The number, the duration and the timing of rewarded and unrewarded visits differed between the various systems. The cows adapted to each feeding system, eating all their rations of concentrates as soon as they were made available.

Adaptation to the feeding system affected several of the general activities, in particular the time spent at the feeding rack and the time spent lying in the cubicles. With the fixed-11-time system, new feeding cycles started at times when many cows were lying down. Under these conditions the lowranking cows sometimes had to wait a long time before they could enter the station, which resulted in a reduced lying time for them.     

Fan cooling of the resting area in a free stalls dairy barn

This summer study evaluated the effect of providing additional fans (cooling) in the resting area within a free-stall dairy barn that had fans and sprinklers in the feeding area and paddock availability. Thirty cows were divided into two homogenous groups and kept in two pens: one had the resting area equipped with two fans (FAN) while no fans were added to the other resting area (CON). Microclimatic parameters, rectal temperature (RT), breathing rate (BR), milk yield, and milk pH traits were recorded. Time budgeting and the behaviour of the cows (time spent in the feeding area, standing and lying in other areas) were also recorded using digital video technology. Two slight-to-moderate heat waves were observed. During the hottest period the daily maximum temperature recorded was 33.5 °C and the daily maximum THI was 81.6. During this period, the BR and RT increased only slightly in both groups, with lower BR (n.s.) in FAN compared with CON. Milk yield was better maintained (n.s.) in FAN compared with CON during the hottest period. The FAN cows showed a greater (P?<?0.05) lying time in the free stalls (9.5 and 8.6 h/day in FAN and CON, respectively), whereas CON cows made greater (P?<?0.05) use of the paddock during evening and late evening hours. Consequently, the total daily lying time was 13.5 h/day in both groups. In conclusion, the results suggest that using fans in the resting area improves cow comfort, which increases use of the resting area. The lying time results also suggest that the benefits of providing ventilation in the resting area might be more evident in barns where there is no paddock.     

Herbage intake and behavioural adaptation of grazing dairy cows by restricting time at pasture under two feeding regimes

The time at pasture of dairy cows is often restricted in the context of extending the grazing season in autumn or at the end of winter. The objective of our study was to evaluate the effects of a restriction of time at pasture on milk production, herbage intake and feeding behaviour in dairy cows according to feeding regime. The four treatments consisted of 4 h or 8 h of time at pasture per day tested under two feeding regimes combining rate of supplementation and herbage allowance: either a high rate of supplementation (10 kg dry matter (DM) of a maize silage-soya bean meal mixture in the ratio 87 : 13 on a % DM basis) with a low herbage allowance (6 kg DM/cow per day above 5 cm), or a low rate of supplementation (5 kg DM of the same supplement) with a high herbage allowance (11 kg DM/cow per day). The study was carried out according to a 4 × 4 Latin square design with four 2-week periods, with 48 mid-lactation Holstein cows. The cows in the 4-h treatment had access to pasture from 0900 h to 1300 h and those in the 8-h treatment from 0900 h to 1700 h. The supplement was given at 1830 h. When time at pasture was reduced from 8 h to 4 h per day, herbage intake decreased (9.9 v. 8.1 kg DM, P < 0.001), along with a fall in milk production (22.3 v. 21.2 kg, P < 0.001) and milk protein concentration (30.1 v. 29.6 g/kg, P < 0.001), while milk fat concentration increased (39.4 v. 39.9 g/kg, P < 0.05). The effect of time at pasture on milk production was slightly more marked on the low-supplement feeding regime (interaction P < 0.06). Reducing time at pasture by 4 h led to a sharp decrease in grazing time (327 v. 209 min, P < 0.001), but strongly increased the pasture intake rate (31 v. 39 g DM/min, P < 0.001) and the proportion of time spent grazing (0.68 v. 0.87, P < 0.001). Cows showed a stronger motivation for grazing when receiving the low-supplement feeding regime. In conclusion, we showed that reducing time at pasture from 8 to 4 h for cows receiving 5 to 10 kg DM of a maize silage-based supplement decreased moderately milk production and herbage intake, because of the capacity for behavioural adaptation by the grazing dairy cows.     

The effect of omitted milking on the behaviour of cows in the context of cluster attachment failure during automatic milking

In robotic milking there is always a slight chance of failure to attach the milking cluster. Attachment failure is most likely for cows whose udder conformation is less convenient for robot attachment. In general, after milking failure cows try to revisit the milking robot if they are not sent to a separate area. Since it is difficult to estimate the effect of milking failure on such a cow and her welfare in conditions of robotic milking, a specific 16-day trial was conducted on 12 cows. These cows were milked in a milking parlour with six milking stalls. Each afternoon milking, three cows were not milked. All the cows were closely observed in the cubicle house for 1 h after the afternoon milking. Thereafter, all cows were brought to the milking parlour the third time and the three unmilked cows were milked. In total, each cow was observed 12 times after milking and four times after omitted milking. The following behavioural traits were registered: time budget for the 1 h, occurrence and time until eating, drinking, lying, urination and defecation, and aggressive interactions. Milking order was defined on the basis of how often a cow came to the milking parlour in the first batch of six cows. Moreover, the data related to the milk yield and the use of the automatic feeding installation with the complete diet were analysed. After omitted milking, only the cows from the first batch stood longer in cubicles (14.2 min of 1 h) and lay less (5.4 min of 1 h) than milked cows of the same batch (respectively 7.0 min and 16.3 min for standing and lying in cubicles) (P<0.01). After omitted milking, cows urinated earlier and more frequently (64.5%) than milked cows (36.3%) (P<0.002) (both batches). There were no statistically significant differences in eating time and feed intake after milking and omitted milking. Milk yield per cow averaged 24.9 kg during days with omitted (delayed by 1 h) milking and 25.3 kg during the days without omitted milking (P<0.05). It was concluded that cows show some signs of discomfort after omitted milking (urination); this discomfort seemed to be greater in cows coming earlier to the milking parlour (afterwards they preferred to stand rather than to lie). The 60% of cases of milk leakage found after omitted milking indicates that failed cluster attachment can be accompanied by an extra risk factor for the occurrence of mastitis. However, omitted milking as a treatment did not influence feeding and aggressive behaviour or milking order when unmilked cows were brought to the milking parlour the third time together with the milked cows. Our methods and results can be useful for estimating the effects of robot milking failures on a cow. Future studies should pay particular attention to high-yielding cows and to longer periods of delayed milking.     

An evaluation of mattresses and mats in two dairy units

In order to investigate the relative merits of mats and mattresses in terms of cow comfort, production and performance, 29 cows were housed on ethylethene vinyl acetate (EVA) mats and 29 on mattresses of loose rubber crumb with a polypropylene cover, at each of two similar dairy units (SAC Auchincruive and Myerscough). Both mats and mattresses were newly installed at the start of the trial. The cows were housed in the autumn after calving. Milk yield was recorded daily. Cows were weighed and scored for body condition, locomotion, dirtiness and hock and knee injury at fortnightly intervals. Feed offered was recorded daily and refusals were weighed weekly. Monthly milk records of milk yield, milk composition and somatic cell count data were available for both herds. In addition, 24 h behavioural observations of 15 core cows in each group were made at weeks 0, 2, 4, 6, 8, 16, and 32 post-housing. There was no difference between cows on mats and mattresses in milk yield, composition or quality; in feed intake; in weight loss or body condition score; in severe hock or knee injury, or in the incidence of lameness. Cows on mattresses tended to have slightly higher total dirtiness scores than those on mats (7.06 vs. 6.95, P=0.074) and had dirtier udders (mattress, 7.50 vs. mat, 6.52, P<0.05). However, over the whole housing period, cows on mattresses spent longer feeding, ruminating and lying and a greater proportion of their lying time was spent ruminating. They spent less time standing doing nothing (idling) than cows on mats and less time idling in cubicles. Cows on mattresses appeared to adapt to housing more quickly than those on mats. Overall, neither mat nor mattress gave advantages in terms of production or performance, cows were slightly cleaner on mats but behavioural indices suggest that cow comfort was greater on mattresses.     

Influence of digital dermatitis and sole ulcer on dairy cow behaviour and milk production

The aim of the study was to investigate whether the presence of digital dermatitis (DD) and sole ulcer (SU) in dairy cows was associated with changes in behaviour and milk production. Swedish Red and Swedish Holstein cows (mostly in the first to second lactation) were housed in a cubicle system with automatically scraped passageways. After maintenance claw trimming of all the cows in the herd, 10 cows with DD and 10 cows with SU were selected. For each DD- or SU-affected cow, a healthy control cow, matched according to breed, age, parity and lactation stage, was selected. The behaviour of each of the 20 focal cows was observed for 1 h during 2 to 3 weeks after claw trimming (WACT; period 1) and for 1 h during 5 to 6 WACT (period 2). Milk production parameters: energy-corrected milk (ECM), fat and protein percentages and somatic cell counts (SCCs) were recorded once monthly. Lameness was scored once at the start of the study and cows with SU and DD showed more score 2 lameness (42% v. 31%) than the healthy cows (12%). Most differences in behaviour were found during 2 to 3 WACT when DD- and SU-affected cows were lying less (P = 0.001 and P = 0.012, respectively) than healthy cows. Ruminating while standing was performed more in DD-affected cows (P < 0.001) and tended to be performed more in SU-affected cows (P = 0.079) than their controls. Vigilance was performed more in DD- and SU-affected cows than in healthy cows (P < 0.001 and P = 0.047). Cows with DD produced approximately 5.5 kg less ECM per day both at 2 to 3 WACT (P = 0.022) and at 5 to 6 WACT (P = 0.017) than healthy cows, whereas SU-affected cows tended to produce less ECM at 5 to 6 WACT (P = 0.059). No differences in milk fat and protein or SCC were found. It may be concluded that DD-affected cows showed a stronger behavioural response to the claw disease than the SU-affected cows. This shows the importance of regular claw checking and claw trimming of the cows in order to avoid the negative effects on behaviour and milk production.     

Effect of time at pasture combined with restricted indoor feeding on production and behaviour in dairy cows

Extremely high nutrient loads have been reported in grazed grassland regimes compared with cutting regimes in some dairy systems that include the use of supplemental feeding. The aim of this study was, therefore, to investigate the effects on productivity and behaviour of high-yielding dairy cows with limited access to indoor feed and restriction in the time at pasture in a continuous stocking system. During a 6-week period from the start of the grazing season 2005, an experiment was conducted with the aim of investigating the effect of restrictive indoor feeding combined with limiting the time at pasture on the productivity and behaviour of high-yielding dairy cows (31.0 ± 5.4 kg energy-corrected milk) in a system based on continuous stocking. The herd was split into three groups allocated to three treatments consisting of 4, 6.5 and 9 h at pasture, respectively. Each group of cows grazed in separate paddocks with three replicates and was separately housed in a cubicle system with slatted floor during the rest of the day. All cows were fed the same amount of supplement, adjusted daily to meet the ad libitum indoor intake of the cows at pasture for nine hours. The herbage allowance was 1650 kg dry matter (DM) per ha, and the intake of supplemental feed was 9.1 kg DM per cow daily. The limitation of the time at pasture to 4 h in combination with restrictive indoor feeding reduced the daily milk, fat and protein yield and live weight compared with 9 h of access to pasture. The proportion of time during which the cows were grazing while at pasture increased from 0.64 to 0.86 and the estimated herbage intake per h at pasture decreased from 2547 g DM to1398 g DM, when time at pasture changed from 4 to 9 h. It can be concluded, that in systems with a high herbage allowance, the cow was able to compensate for 0.8 of the reduction in time at pasture by increasing the proportion of time spent grazing and presumably also both the bite rate and mass, although the latter two have not been directly confirmed in the present study.     

Lying laterality and the effect of IceTag data loggers on lying behaviour of dairy cows

Lying behaviour is a useful indicator of cow comfort, but can be time consuming to measure. Data loggers are commonly used to automatically record behavioural activity but may influence the animal's behaviour. We investigated the effect of a new model of the IceTag data logger (IceTag Sensor, IceRobotics© Ltd, Edinburgh, UK) on lying behaviour of forty dairy cows. Smaller Hobo^® Pendant G data loggers (Onset Computer Corporation, Pocasset, MA) were attached to the hindlegs of all cows balanced for left and right and measured total duration of lying time, frequency and mean duration of lying bouts and the percent of time lying down on each side. Sixteen cows were semi-randomly split into two groups depending on the position of the IceTags on the inside of the leg (medial) or the outside (lateral). Each cow experienced four treatments in a Latin square design: no IceTag data logger attached as a control (C); one IceTag data logger on the left hind leg (L), one IceTag data logger on the right hind leg (R), and a IceTag data logger on both hind legs (B). Each treatment lasted for 6 days. As part of a separate study, lying laterality data from 24 cows with an IceTag data logger attached to the lateral part of each hindleg was used. On average, cows (n = 39) spent 47.5% of their time lying on the right side during a 24-h period. However, there was a large variation of time spent lying on the right side ranging from 25.1% to 65.7%. There was no significant effect of IceTag location (medial or lateral) or treatment (C, L, R, B) on total lying time, frequency of lying time, duration of lying bouts or percentage of time lying on each side. In summary, IceTags did not affect lying behaviour in dairy cows, allowing them to be reliably used in research as a high tech tool to measure activity. Overall as a group, cows show no preference for lying on one particular side, but individual cows do show a distinct preference.     

Evidence for the effect of tryptophan on the pattern of food consumption in free feeding and food deprived rats.

The effects of injections of 50 mg/kg L-tryptophan upon meal size, meal frequency, rate of eating and satiety ratios were measured in rats whose feeding behaviour was monitored continuously over 24-h periods. A number of precautions were taken to minimize the effects of novel or stressful experimental procedures, to prevent the contamination of behaviour during periods of data collection and to maximise the detection of subtle effects on behaviour. In freely-feeding rats tryptophan brought about a significant diminution in the 24-h food intake and significantly reduced meal size. When food deprived rats were tested under similar circumstances tryptophan significantly reduced the size of the first large meal taken after the deprivation period and markedly extended the duration of the post-meal interval. The conditions adopted in this study to improve the sensitivity of the behavioural assay for feeding have made possible the detection of certain small but clear effects of tryptophan on food consumption in rats.     

The effect of irregular feeding times on the behaviour and growth of dairy calves

The objective of this study was to examine the effects of predictable vs. unpredictable management routines on the behaviour, production and health of dairy calves. Three different feeding schedules for milk-fed dairy calves were compared. All calves received milk twice a day, and had free access to concentrate, hay and water. Three groups of 12 calves (divided on two trials) were exposed to one of the following treatments from the age of 5 days to 9 weeks: group C (control) received milk at the same time every day, at 0700 and 1400. Group OD (occasional deviation) received the milk at the same time every day except on treatment days, one in week 5 and one in week 8, where they were fed 3 h later. Group IR (irregular schedule) received milk at irregular times throughout the experimental period. The first daily feeding took place between 0600 and 1300 and the second one between 1300 and 2100. When the calves were 5 and 8 weeks old, the behaviour of eight calves from each group was videorecorded for two days (48 h). The following behaviour was recorded: frequency and duration of lying bouts and frequency of comfort behaviour (defined as licking or scratching own body), eating, drinking, other oral behaviour and extending the head through the feeding barrier (HTB). The milk and concentrate consumption of the calves was measured and the calves were weighed weekly. Diseases were recorded.The results showed that at the age of 5 weeks, the calves in group IR differed from the control group C by performing more eating behaviour both on the control day (27.5 vs. 15.5; p<0.05) and the treatment day (28.8 vs. 18.3; p<0.05). At the age of 8 weeks, no differences were found in the behaviour between groups IR and C. When the OD calves were 5 weeks old, they responded to the delayed feeding by increasing drinking behaviour (14.5 vs. 9.0; p<0.05). When they were 8 weeks old, they showed increased frequency of comfort (195 vs. 122; p<.05), eating (37.5 vs. 27.9; p<0.05) and HTB behaviour (19.8 vs. 7.4; p<0.001) on the treatment day compared to the control day. The IR group did not respond to the same treatment except for a slight increase in drinking behaviour (9.6 vs. 6.5; p<0.05) at the age of 8 weeks. No differences were observed in the frequency or length of lying bouts, nor health or production parameters between the three groups.It is concluded that a predictable feeding schedule may not be very important for milk-fed dairy calves. However, when the calves are customised to predictable feeding times, occasional deviations from that schedule may cause frustration when their expectations are not fulfilled.     

A note on overdispersion as an index of behavioural synchrony: a pilot study in dairy cows

We developed a method for studying the synchrony of behaviour based on calculations of overdispersion of a binomial process. The lying behaviour of cows was investigated under two different housing units inside the same barn. The first unit housed 30 cows undergoing conventional milking and the second unit housed 27 cows undergoing automatic milking. The lying behaviour of the cows was observed over 3 weeks in 12 periods of 6 h each. Every 5 min, we counted the number of cows lying down in the cubicles. As external cues, like feeding and conventional milking, can promote synchrony in dairy cows, we expected that cows conventionally milked would show more behavioural synchrony than automatically milked cows. Cows lied down synchronously in both units (overdispersion 1.67, P < 0.01). Lying synchrony tended to be slightly bigger in automatically than in conventionally milked cows (overdispersion 1.76 v. 1.58, P = 0.09), although the proportion of cows lying down was on average greater in conventionally than in automatically milked cows (60.7% v. 45.6%). This suggests that synchronized lying behaviour in cows is a constant phenomenon that depends on social facilitation rather than on external cues. The overdispersion index appears to be a useful tool for studying the synchrony of animal behaviour when observations are made at the group level.     

Timing of visits to the concentrates feeding station by dairy cows

Dairy cows can be fed concentrates in feeding stations with automatic feeding systems. This paper discusses factors which may influence the timing of the cows' visits to the feeding station. Factors affecting the dairy cows' behaviour just before and just after the visit, and information which might be used by the cows in deciding whether to visit the feeding station are investigated.

An investigation was carried out with a group of 20 lactating dairy cows. In successive 3-week experimental periods the cows were fed concentrates with three different automatic concentrates feeding systems (fixed-7-time, fixed-3-time and variable-time systems). Twenty-four hour behavioural observations recorded the cows' general activities while the number and duration of visits to the feeding station and the intake of concentrates were recorded automatically.

The three concentrates feeding systems each gave rise to a typical pattern of visits (total number of visits, and timing of rewarded and unrewarded visits). However, the pattern of general activities was not affected by the concentrates feeding system.

The cows' general activities both before and after their visits to the feeding station were significantly affected by the time of the day. However, the cows' possible knowledge about their chances of receiving concentrates did not affect their general activities significantly. The results suggest that the cows fitted their visits to the concentrates feeding station into their normal daily routine. For instance, the cows did not often leave the cubicles solely to pay a visit to the feeding station. It was also not possible to show that the cows spent more time eating roughage after an unrewarded visit to the concentrates feeding station than after a rewarded visit.

The cows could have learned the times of the day when concentrates were available and that at certain times they could also expect concentrates when another cow visited the feeding station and received concentrates. However, it was shown that the cows visited the concentrates feeding station throughout the 24-h period, which means that the timing of their visits was not affected by the time of day. The results suggested that, to some extent, the cows responded to information from the feeding station. Rewarded visits were more often and more consistently followed by a visit by another cow than were unrewarded visits.

It is concluded that the cows: (i) did not respond to variation over the 24-h period in their chances of obtaining concentrates; (ii) did not always respond to information from the feeding station. The cows apparently chose a strategy of paying regular visits to the feeding station, because the cost for such visits is low and the reward is sufficiently high.     

Peri-partum posture and behaviour of gilts and the location of their piglets in lines selected for components of efficient lean growth

Peri-partum posture and behaviour of gilts from lines selected for different components of efficient lean growth were studied to determine if behavioural changes may have been associated with the observed responses in reproductive performance. The proportions of time that gilts expressed defined posture and behaviour traits and the locations of their piglets were determined from video recordings of observations made at 5min intervals in the period extending from 2h pre-farrowing to 2h post-farrowing. The 137 gilts studied were from four pairs of Large White lines which had been divergently (high and low) selected for either daily food intake (DFI), lean food conversion efficiency (LFC), lean growth rate on ad libitum feeding (LGA) or lean growth rate on a restricted feeding scale (LGS).Almost all the significant (P<05) changes occurred in the LGS pair of lines. In the pre-farrowing period, relative to the low LGS gilts, high LGS gilts spent a higher proportion of their time lying on their sides (0.92 versus 0.69), and less time in the upright postures of standing, sitting or lying on their bellies (0.08 versus 0.33) and engaging in nesting behaviour (0.02 versus 0.10). During farrowing, high LGS gilts again lay on their sides more often than low LGS gilts (0.96 versus 0.80) and were upright less often (0.04 versus 0.20). High LGS gilts changed posture less often than low LGS gilts (0.05 versus 0.31) but were more often alert (0.79 versus 0.61). During farrowing, high LGS piglets were seen less often at their mother's head, back and vulva or at the creep than low LGS piglets (0.06 versus 0.15). Post-farrowing, there were no significant differences between the lines, almost all gilts lying on their sides with their piglets at the udder. Divergent selection for components of efficient lean growth rate on ad libitum feeding was not associated with consistent responses in gilt posture and behaviour or in piglet location. Selection for high lean growth on restricted feeding had effects on gilt posture and behaviour which may have been beneficial to her welfare and that of her piglets.     

Age dynamics of visually guided behavior and visual evoked potentials of altricial nestlings

Comparative study has been carried out of factors of organization of visually guided feeding behaviour (observation method) and the degree of maturity of the visual mechanisms by the criterion of Wulst EPs formation and of their recovery cycles in normally developing and visually deprived nestlings. In has been established that during the period following the opening of the eyes (5-9th day) the feeding behaviour is connected with diffuse photo-sensitivity of visual mechanisms. Diffuse photo-sensitivity fully provides for natural feeding behaviour at the corresponding stage of development of visual functions. Complete visual deprivation during the whole period of diffuse photo-sensitivity does not influence subsequent development of the visual system.     

Effect of timing of corn silage supplementation to Holstein dairy cows given limited daily access to pasture: intake and performance

The timing in which supplements are provided in grazing systems can affect dry matter (DM) intake and productive performance. The objective of this study was to evaluate the effect of timing of corn silage supplementation on ingestive behaviour, DM intake, milk yield and composition in grazing dairy cows. In total, 33 Holstein dairy cows in a randomized block design grazed on a second-year mixed grass–legume pasture from 0900 to 1500 h and received 2.7 kg of a commercial supplement at each milking. Paddock sizes were adjusted to provide a daily herbage allowance of 15 kg DM/cow determined at ground level. The three treatments imposed each provided 3.8 kg DM/day of corn silage offered in a single meal at 0800 h (Treatment AM), equally distributed in two meals 0800 and 1700 h (Treatment AM-PM) or a single meal at 1700 h (Treatment PM). The experiment was carried out during the late autumn and early winter period, with 1 week of adaptation and 6 weeks of measurements. There were no differences between treatments in milk yield, but 4% fat-corrected milk yield tended to be greater in AM-PM than in AM cows, which did not differ from PM (23.7, 25.3 and 24.6±0.84 kg/day for AM, AM-PM and PM, respectively). Fat percentage and yield were greater for AM-PM than for AM cows and intermediate for PM cows (3.89 v. 3.66±0.072% and 1.00 v. 0.92±0.035 kg/day, respectively). Offering corn silage in two meals had an effect on herbage DM intake which was greater for AM-PM than AM cows and was intermediate in PM cows (8.5, 11.0 and 10.3±0.68 kg/day for AM, AM-PM and PM, respectively). During the 6-h period at pasture, the overall proportion of observations on which cows were grazing tended to be different between treatments and a clear grazing pattern along the grazing session (1-h observation period) was identified. During the time at pasture, the proportion of observations during which cows ruminated was positively correlated with the DM intake of corn silage immediately before turn out to pasture. The treatment effects on herbage DM intake did not sufficiently explain differences in productive performance. This suggests that the timing of the corn silage supplementation affected rumen kinetics and likewise the appearance of hunger and satiety signals as indicated by observed changes in temporal patterns of grazing and ruminating activities.     

Impact of lameness on gait characteristics and lying behaviour of zero grazed dairy cattle in early lactation

The present study examines the impact of lameness on the time budgets and gait of dairy cattle during early lactation. Automated assessment of activity together with an objective method (using video motion analysis) of assessing the gait of the cattle was utilised.Twenty-five Holstein dairy cows were recruited to the study and were assessed during weeks 1, 6 and 12 of lactation. Lying behaviour was measured using IceTag? activity monitors which were attached to the right hind leg of the cow for 4 consecutive days during each study week. Cows were locomotion scored to evaluate the influence of lameness on gait and behaviour of cows. Cows that were lame in a hind limb had significantly shorter fore and hind stride lengths. They also tended (p = 0.06) to have a negative tracking distance and walk at a slower (p = 0.002) speed compared with cows that were considered to be non-lame. Lame cows spent 2 h more time lying down per day in comparison to non-lame cows. Cows spent significantly less time lying down during week 6 of lactation and more time standing in comparison to the cows in week 12. The lying behaviour of cows was not different during weeks 1 and 6 or weeks 1 and 12. Cows were significantly more active during week 1 than week 12 of lactation. However the activity of the cows during week 6 was not different from weeks 1 and 12 of lactation. The present study demonstrates that lameness influences stride characteristics and lying behaviour of zero grazed dairy cows.     

The effect of hunger and cestode parasitism on the shoaling decisions of small freshwater fish

Individual minnows Phoxinus phoxinus and three-spined sticklebacks Gasterosteus aculeatus were provided with a mutually exclusive choice between joining a shoal of conspecifics and foraging alone in a maze. The shoaling decisions and foraging behaviour of individual fish were studied when the fish were satiated and after 24- and 48-h periods of food deprivation. Hunger level was found to have a significant effect on shoaling behaviour. When satiated, fish of both species spent a greater proportion of time within one body length of the shoal and spent less time out of visual contact with the shoal than after periods of food deprivation. The effect of the cestode parasite Schistocephalus solidus on the shoaling behaviour of stickleback hosts was complex. When satiated, infected fish spent less time than uninfected fish within one body length of the shoal, preferring to remain outside the shoal, yet within visual contact, although when food deprived there was no difference in the proportion of time spent by infected and uninfected fish close to the shoal. The possible ecological significance of this change in behaviour is discussed with reference to the manipulation hypothesis of host-parasite interactions.     

The effects of food deprivation on beta-adrenergic responsiveness in male rats

Male rats were deprived of food for varying lengths of time (0-96 h) and their responses to beta-adrenergic stimulation with isoproterenol were tested. Food deprivation for 48 or 96 h attenuated the increase in tail skin temperature normally seen following administration of isoproterenol. The degree of attenuation was dependent on the duration of the deprivation period. Rats deprived of food for 96 h and then refed for 48, 96, or 144 h showed a return of tail skin temperature response to near normal levels. The increase in heart rate observed following administration of isoproterenol was also attenuated following 48 or 96 h of food deprivation. Again, the degree of attenuation was dependent on the duration of the deprivation period. Food deprivation for 96 h led to a decrease in basal plasma levels of T3, T4, and glucose. The increase in plasma glucose following administration of isoproterenol was also attenuated following 96 h of food deprivation. In contrast to the thermal, cardiac, and glucose responses, the dipsogenic response to isoproterenol was increased following food deprivation. The attenuation in beta-adrenergic responses observed in the food-deprived rats might help explain the effects of food deprivation on cold tolerance.     

Does the diurnal pattern of enteric methane emissions from dairy cows change over time?

Diet manipulation and genetic selection are two important mitigation strategies for reducing enteric methane (CH₄) emissions from ruminant livestock. The aim of this study was to assess whether the diurnal pattern of CH₄ emissions from individual dairy cows changes over time when cows are fed on diets varying in forage composition. Emissions of CH₄ from 36 cows were measured during milking in an automatic (robotic) milking station in three consecutive feeding periods, for a total of 84 days. In Periods 1 and 2, the 36 cows were fed a high-forage partial mixed ration (PMR) containing 75% forage, with either a high grass silage or high maize silage content. In Period 3, cows were fed a commercial PMR containing 69% forage. Cows were offered PMR ad libitum plus concentrates during milking and CH₄ emitted by individual cows was sampled during 8662 milkings. A linear mixed model was used to assess differences among cows, feeding periods and time of day. Considerable variation was observed among cows in daily mean and diurnal patterns of CH₄ emissions. On average, cows produced less CH₄ when fed on the commercial PMR in feeding Period 3 than when the same cows were fed on high-forage diets in feeding Periods 1 and 2. The average diurnal pattern for CH₄ emissions did not significantly change between feeding periods and as lactation progressed. Emissions of CH₄ were positively associated with dry matter (DM) intake and forage DM intake. It is concluded that if the management of feed allocation remains constant then the diurnal pattern of CH₄ emissions from dairy cows will not necessarily alter over time. A change in diet composition may bring about an increase or decrease in absolute emissions over a 24-h period without significantly changing the diurnal pattern unless management of feed allocation changes. These findings are important for CH₄ monitoring techniques that involve taking measurements over short periods within a day rather than complete 24-h observations.