The effect of the milking process on oxytocic activity in the blood plasma of cows during oestrous

The purpose of this work was to compare the oxytocic activity of plasma in oestrous cows during milking and for the first and second days following oestrous. Oxytocic activity of blood plasma was measured by the in vitro rat mammary cube assay of van Dongen and Hays. During oestrous, signigicantly lower amounts of oxytocin are released into the bloodstream of cows following milking as compared with the control values.     

Effects of milking frequency on lying down and getting up behaviour in dairy cows

The objective of this study was to investigate if cows milked twice per day have more difficulty lying down and getting up and spend less time lying than cows milked three times per day. Seventeen cows of the Swedish Red and White Cattle Breed were studied, seven of which were milked twice daily (2M) and ten were milked three times (3M) daily. They were kept in individual cubicles, that were closed in the rear end with a rope. They had free access to a mixture of silage, hay and concentrate. The individual cows were video-recorded for 24h every fourth week, starting four weeks after calving for four times. The 2M cows stood significantly longer, 128.11min, than the 3M cows, 64.88min, (P<0.01) during the 4h before morning milking. The 2M cows also had a tendency for longer duration of standing rumination (P=0.059) as well as significantly more bouts of standing rumination (P<0.01) during these hours than the 3M cows. The cows in the 3M group spent less time on the getting up movement (P<0.05) during the 4h before morning milking. The distribution of the lying bouts during these 4h differed significantly between the groups, where the 3M cows had fewer lying bouts shorter than 15min and more lying bouts longer than 90min. The results indicate that milking three times a day contributes to increased comfort in high-producing dairy cows.     

The effect of pre-partum milking on the transfer of immunoglobulin into mammary secretion of cows.

The significance of local effects associated with mammary involution on transfer of immunoglobulin and especially on the selective transfer of IgG1 into mammary secretion of cows approaching parturition has been determined. This was carried out by measuring the changes in the concentration of IgG1, IgG2, IgM and IgA in serum and mammary secretion of 5 cows in which two mammary glands were milked continuously (twice daily) during the period preceding parturition, while the other two glands were allowed to undergo normal involution. In the secretion of unmilked glands of all cows there was a substantial increase in the concentration of IgG1 as cows approached parturition. In contrast, the increases in the concentration of IgG1 and in the selective index for IgG1 of milked glands were either virtually non-existent (1 cow) or generally reduced in magnitude and delayed in time of onset (4 cows). It is clear from the results that continued milking of a mammary gland throughout pregnancy tends to maintain milk production in the milked gland and at the same time reduces the massive selective transfer of IgG1 into secretion of that gland.     

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.     

The effects of conditioning to suckling, milking and of calf presence on the release of oxytocin in dairy cows

The aim of the study was to record the oxytocin (OT) release during milking (M) without or with calf presence, suckling (S) and finally calf removal just before the next milking in cows during postpartum or early lactation periods. Furthermore, the release of OT was examined during S and M in unknown surroundings (parlour). A total of 20 Brown Swiss cows kept under loose housing environment were used in our experiment. In both periods, the cows were milked twice daily at 07.00 and 18.00h and suckled three times daily at 09.00, 14.00 and 20.00h in the stall (tie housing). In the postpartum period, 13 cows were suckled and milked in the presence of their calves in the stall for the first 5 days of postpartum. Five from seven primiparous cows were additionally suckled by their own calves in the parlour on day 5 at 20.00h. On day 6, calves were separated and moved from mothers to the calf barn 10min before morning M. After evening milking cows were relocated to the herd within the same stable and milked in the parlour for a period of 4 weeks without contact to their calf. For control, additional seven primiparous cows without calf presence (not suckled) were also milked in the tie housing. In the early lactation period, suckled cows were moved back to the tie housing 2 days before the start of two consecutive days of S by their own calves and milking. Afterwards, 10min before M calves were separated again. Before S, two consecutive M were considered as controls. Results: The S stimulus during postpartum resulted in a higher OT release as compared with M in the calf presence and M after calf separation but not during M of not suckled cows. S in parlour reduced OT release. However, when not suckled primiparous cows were first milked in parlour, OT release was more reduced and in some cows total inhibition was observed. In early lactation during the first S, release of OT was lower than during control M, but increased gradually with repeated S and reached a maximum already on the second day. After two S, during evening M, the M related OT release was reduced as compared with controls. Calf removal 10min before M reduced OT release as compared with control M or M in calf presence. In conclusion, the calf presence and its removal can negatively influence OT secretion during M. Conditioning to machine milking caused a short-term reduction of OT release during first suckling, which normalised within 1 day.     

The effect of hypoxia on locomotor performance and behaviour during escape in Liza aurata

Escape performance was investigated in the golden grey mullet Liza aurata exposed to various levels of oxygen: >85 ( i.e. normoxia), 50, 20 and 10 % air saturation. Since the golden grey mullet performed aquatic surface respiration when air saturation approached 15–10 %, escape performance was tested at 10 % air saturation with and without access to the surface (10 % S and 10 % C, respectively). Various locomotor and behavioural variables were measured, such as cumulative distance, maximum swimming speed, acceleration, responsiveness (per cent of responding fish), response latency and directionality. Golden grey mullet showed a decrease in responsiveness when the oxygen level was reduced to 10 % air saturation, whether the surface access was obstructed or not. Hypoxia did not have any effect on the response latency. Cumulative distance and maximum swimming speed over a fixed time were significantly different between normoxic conditions and 10 % C, while no differences were found in maximum acceleration. While the fish's 'C‐bend' was mainly directed away from the stimulus in normoxia, the proportion of away and towards 'C‐bend' was random when the oxygen was ≤20 % air saturation. This suggested an impairment of the left‐right discrimination at the initiation of the fast start. Hypoxia affected golden grey mullet escape performance mainly through an impairment of responsiveness and directionality, while locomotor performance was affected only in severe hypoxia when the surface was obstructed. The study showed that, in addition to forcing the fish to the surface as shown by previous studies, hypoxia may also reduce fish elusiveness facing a predator by directly impairing its escape performance.     

Effect of calf suckling on oxytocin,prolactin, growth hormone and milk yield in crossbred Gir x Holstein cows during milking

This study evaluated the effect of different milking managements on oxytocin, prolactin and growth hormone release in Gir x Holstein cows. Six cows were suckled by their calves, before and after milking (SM group); another six cows were submitted to exclusive milking (M group). High OT levels were observed during suckling of the SM group, however both groups had similar levels of OT during milking. The SM group presented PRL levels significantly higher than the M group, however only during suckling. For GH levels, the SM group showed higher levels than the M group, however this difference was significant only during the first suckling, cleaning of the teats and at the beginning of machine milking. Despite these results, SM cows produced more milk (milking plus suckling) than M cows, however milk obtained by milking was similar for both groups.     

Effect of milking frequency and nutritional level on aspects of the health and welfare of dairy cows

The objective of this experiment was to investigate the effect of milking frequency and nutritional level on some aspects of animal health. Holstein-Friesian cows (n = 60) were assigned post calving to a factorial arrangement of treatments; twice a day (TAD) milking on a high or low nutritional level; once a day (OAD) milking on a high or low nutritional level. Milking characteristics were recorded daily. Blood samples to evaluate changes in the composition of the blood cells, milk leakage, udder tension and locomotory ability were measured on four occasions. Teat-ends were classified for hyperkeratosis (HK) monthly post partum. TAD had longer daily milking times (P < 0.001) compared with OAD cows. There was no effect of milking frequency or nutritional level on morning milking time, time to milk letdown or peak milk flow rate (P>0.05). High nutritional level cows had higher average flow-rates (P < 0.05) than low nutritional level cows. Neither milking frequency nor nutritional level affected HK (P>0.05). However, HK values were positively correlated with daily milking time for OAD cows for 6 months of lactation (P < 0.05). This correlation was significant (P < 0.01) for cows milked OAD on high nutrition during the peak lactation period. OAD cows had higher levels of milk leakage compared with TAD cows during the month of May (P < 0.01). Cows on high nutrition milked OAD showed higher udder firmness scores than cows milked once or twice daily at the low nutrition level in June and July (P < 0.05). OAD cows had higher locomotion scores compared with TAD cows (P < 0.001). Locomotion and udder firmness scores were significantly correlated for OAD in June (P < 0.05). OAD cows had lower blood lymphocyte counts, numerically higher counts of neutrophil and a higher monocyte count at peak lactation compared with TAD cows suggesting that OAD cows had altered immune responses. The increase in milk leakage, higher udder firmness and locomotion scores in conjunction with changes in blood cells, suggests that OAD milking may have caused some discomfort to the cows during peak lactation. A reduction in the concentrate input to OAD cows during this period could ameliorate this problem.     

The effect of a mixed-management system on the release of oxytocin, prolactin, and cortisol in ewes during suckling and machine milking

Milk yield and plasma oxytocin (OT), prolactin (PRL), and cortisol (CORT) during suckling and machine milking were measured in multiparous ewes subjected to a mixed management system of 3 sucklings and two daily milkings. Peak hormones were significantly increased and were similar during suckling and milking for PRL (181 vs. 163.3 ng x mL(-1)) and CORT (12.5 vs. 11.5 ng x mL(-1)). During the period of exclusive suckling, OT was always significantly released (90.3 pg x mL(-1)); however, during the period of mixed management, OT concentrations only increased during suckling compared to milking (91.7 vs. 13.1 pg x mL(-1)). The mean volume of milk obtained during suckling (632 mL) was significantly higher than during milking (255 mL). Thus, during a mixed management system, oxytocin and prolactin releases are not under similar central regulation. A mixed system, without OT release during milking, does not contribute to accelerate the conditioning of ewes for machine milking.     

The effect of PMSG-priming on subsequent superovulatory response in dairy cows

Superovulation was induced in 56 dairy cows to evaluate the effect of two different regimens using pregnant mare serum gonadotropin (PMSG). Thirty-two cows (controls) were superovulated between Days 9 and 12 of the estrous cycle with a single dose of PMSG (2 800 IU), while remaining 24 cows (PMSG-primed) received 200 IU of PMSG on Day 4 of the estrous cycle and subsequently a single dose of PMSG (2 800 IU) between Days 8 and 12. The cows in both treatments were each given 0,5 mg of cloprostenol at 48 h after the superovulatory PMSG treatment. They were then artifically inseminated twice, 48 h and 72 h later. Embryos were recovered at sloughter between Days 2 and 5 of the cycle and morphologically evaluated. The number of corpora lutea (CL) in the ovaries of the cows was recorded. The mean number of CL (7.2 vs 17.8) was significantly higher (P 0.01) for PMSG-primed cows. The percentage of recovered ova (60.5 vs 70.2 %) and good embryos (79.3 vs 70.7%) were not significantly different between groups. The percentage of fertilized ova (91.4 vs 83.8%) was significantly (P 0.025) greater for the controls. Results of the study indicate that PMSG-priming increased the ovulation rate in the cows superovulated with PMSG.     

The effect of glyprolines on stressogenic disorders in the rat behaviour

Protective and antistress effects of three glyprolines--PGP, PG and GP, were studied. Stress influences produced typical changes of behavioural activity of rats in the elevated pluz-maze and the hole-board tests. These changes suggest a significant enhancement of anxiety and a drop of the level of orientation-investigative activity. A preliminary (15 minutes before stress agent) intraperitoneal administration of PGP or GP in doses of 3.7 microm/kg significantly decreased stress disturbances of behaviour. Analysis of these data shows to the possibility of PGP and GP influences on the CNS structures, which take part in the organism reciprocal reactions to stress factor. The peptide GP at equimolar dose didn't possess pronounced protective properties and just slightly decreased stress disturbance of behavioural activity of rats.     

The effect of sweet stimuli on oral behaviour in the chicken

The oral behaviour of the chicken was investigated in responseto a variety of concentrations of fructose, sucrose and carboxymethylcellulosesolutions. Both fructose and sucrose produced a similar increasein beak and tongue movements whereas an equivalent increasewas only elicited by carboxymethylcellulose at much higher viscosities.An increase in head shaking behaviour only occurred when thebirds were stimulated with sucrose solutions. Increases in beakwiping behaviour occurred only with sucrose and carboxymethylcellulosesolutions. It was concluded that no single characteristic ofthe stimulus chemical was responsible for all the differentbehaviours shown.     

The effect of a corona discharge on a lightning attachment

The interaction between the lightning leader and the space charge accumulated near the top of a ground object in the atmospheric electric field is considered using analytical and numerical models developed earlier to describe spark discharges in long laboratory gaps. The specific features of a nonstationary corona discharge that develops in the electric field of a thundercloud and a downward lightning leader are analyzed. Conditions for the development of an upward lightning discharge from a ground object and for the propagation of an upward-connecting leader from the object toward a downward lightning leader (the process determining the point of strike to the ground) are investigated. Possible mechanisms for the interaction of the corona space charge with an upward leader and prospects of using it to control downward lightning discharges are analyzed.