Ferenc Ruff

Rumination time and reticuloruminal temperature as possible predictors of dystocia in dairy cows

The objectives of this study were to explore changes of rumination time and reticuloruminal pH and temperature of dairy cows and heifers (means ± standard deviation; age = 5.8 ± 1.9; parity = 2.7 ± 1.4; body condition score = 3.2 ± 0.2) with eutocic (EUT, n = 10) and dystocic calving (DYS, n = 8). The recording period lasted from 3 d before calving until 7 d in milk. For the comparison of rumination time and reticuloruminal characteristics between groups, time to return to baseline (the time interval required to return to baseline from the delivery of the calf) and area under the curve (AUC; both for prepartum and postpartum periods) were calculated for each parameter. Rumination time decreased from baseline 28 h before calving both for EUT and DYS cows; after 20 h before calving, it decreased to 32.4 ± 2.3 and 13.2 ± 2.0 min/4 h between 8 and 4 h before delivery in EUT and DYS cows, respectively, and then it decreased below 10 and 5 min during the last 4 h before calving. Until 12 h after delivery, rumination time reached 42.6 ± 2.7 and 51.0 ± 3.1 min/4 h in DYS and EUT dams, respectively; however, AUC and time to return to baseline suggested lower rumination activity in DYS cows than in EUT dams for the 168-h postpartum observational period. Reticuloruminal pH decreased from baseline 56 h before calving both for EUT and DYS cows, but did not differ between groups before delivery. Reticuloruminal pH showed a decreasing tendency and clear diurnal variation after calving for both EUT and DYS cows, with slightly higher AUC values in DYS cows. In DYS cows, reticuloruminal temperature decreased from baseline 32 h before calving by 0.23 ± 0.02°C, whereas in EUT cows such a decrease was found only 20 h before delivery (0.48 ± 0.05°C). The AUC of reticuloruminal temperature calculated for the prepartum period was greater in EUT cows than in DYS cows. During the first 4 h after calving, reticuloruminal temperature decreased from 39.68 ± 0.09 to 38.96 ± 0.10°C and from 39.80 ± 0.06 to 38.81 ± 0.08°C in EUT and DYS cows, respectively, and reached baseline levels after 35.4 ± 3.4 and 37.8 ± 4.2 h after calving in EUT and DYS cows, respectively. Based on our results, continuous monitoring of changes in rumination time and reticuloruminal temperature seems to be promising in the early detection of cows with a higher risk of dystocia. Depressed rumination activity of DYS cows after calving highlights the importance of the postpartum monitoring of cows experiencing difficulties at calving. The effect of dystocia on postpartum reticuloruminal pH was not pronounced.

Hypothalamic-pituitary-adrenal and cardiac autonomic responses to transrectal examination differ with behavioral reactivity in dairy cows.

Behavior, hypothalamic-pituitary-adrenal axis, and cardiac autonomic nervous system (ANS) activity were evaluated in response to transrectal examination in nonlactating Holstein-Friesian cows with different behavioral reactivity. According to behavioral reactions shown to the procedure of fixing the heart rate (HR) monitors, the 20 cows with the highest and the 20 cows with the lowest behavioral reactivity were involved in the study (high responder, n=20; and low responder, n=20, respectively). Activity of the ANS was assessed by HR and HR variability parameters. Blood and saliva were collected at 5 min before (baseline) and 0, 5 10, 15, 20, 30, 40, 60, and 120 min after the examination to determine cortisol concentrations. The examination lasted for 5 min. Cardiac parameters included HR, the root mean square of successive differences between the consecutive interbeat intervals, the high frequency (HF) component of heart rate variability, and the ratio between the low frequency (LF) and HF parameter (LF/HF). Following the examination, peak plasma and saliva cortisol levels and the amplitude of the plasma and saliva cortisol response were higher in high responder cows than in low responders. Areas under the plasma and saliva cortisol response curves were greater in high responder cows. Plasma and salivary cortisol levels correlated significantly at baseline (r=0.91), right after examination (r=0.98), and at peak levels (r=0.96). Area under the HR response curve was higher in low responder cows; however, maximum HR and the amplitude of the HR response showed no differences between groups. Minimum values of both parameters calculated for the examination were higher in high responders. Following the examination, response parameters of root mean square of successive differences and HF did not differ between groups. The maximum and the amplitude of LF/HF response and area under the LF/HF response curve were lower in low responder cows, suggesting a lower sympathetic activation of the ANS. Although changes in behaviors indicated that the procedure was painful for the animals, no differences were observed either in vocalization or in attendant behavior between groups during the examination. Our results demonstrate that behaviorally more reactive animals exhibit increased plasma and salivary cortisol concentrations and higher cardiac autonomic responsiveness to transrectal examination than less reactive cows. Salivary cortisol may substitute for plasma cortisol when assessing response of cattle to stress.

Assessment of heat stress in 7-week old dairy calves with non-invasive physiological parameters in different thermal environments

We estimated thermal stress in 7-week old Holstein bull calves during a warm episode in summer to study acute physiological responses of calves to heat stress. Data were collected over a 5-day period: day 1 (control), day 2 (heat stress), and a 3-day post-stress period in shaded (n = 8) and unshaded (n = 8) thermal environments. On the control day, both groups were shaded. Thermal environment was characterized by relative humidity, ambient temperature, and the temperature–humidity index (THI). Physiological variables included respiratory rate, rectal temperature, ear skin temperature and heart rate. Correlations between animal-based and meteorological indices were calculated, and ambient temperature correlated slightly better with physiological measures than THI. Rectal temperature was the only animal-based parameter that showed stronger correlations with the thermal indices when calculated for the shaded than for the unshaded environment [r = 0.42 vs. r = 0.47, P = 0.032 (ambient temperature), r = –0.39 vs. r = –0.45, P = 0.012 P = 0.015 (relative humidity), r = 0.41 vs. r = 0.46, P = 0.022 (THI)]. No differences were found between groups during the control day for any of the physiological parameters. During days 2 and 3, average and maximal values of respiratory and heart rates were higher in unshaded calves than in shaded ones. Maximal respiratory rates were in average by 25.9, 17.8 and 10.1 breaths/min lower in shaded calves than in unshaded calves for days 2, 3 and 4, respectively (P < 0.001, P < 0.001 and P = 0.024). Maximal heart rate was 127.4 ± 8.5 vs. 99.2 ± 6.3 beats/min on the heat stress day (P < 0.001), and 121.0 ± 6.9 vs. 103.4 ± 7.7 beats/min on day 3 (P = 0.006) in unshaded and shaded calves, respectively. Maximal body temperatures were higher measured either in the rectum or on the ear skin in unshaded calves than in shaded ones (with 0.5 and 1.6°C, P = 0.040 and P = 0.018, respectively), but only on the heat stress day. Based on our results, shading of young calves may be adequate for alleviating acute heat stress in continental regions. Ambient temperature is appropriate to estimate acute heat stress in dairy calves.

Association between human and animal thermal comfort indices and physiological heat stress indicators in dairy calves

ABSTRACT Warm summer episodes have a significant effect on the overall health and well‐being of young cattle; however, it is not known which temperature measure should be used for estimating heat stress in dairy calves. In this study, generalized linear mixed‐effects models were used to estimate the relationships between thermal comfort indices and animal‐based heat stress indicators in sixteen Holstein bull calves that were housed in individual calf hutches. Data were collected under continental weather characteristics over a 5‐day period: day 1 (lower‐temperature day), days 2 and 3 (heat stress days), and a 2‐day post‐stress period. Relative humidity, ambient temperature, the heat index, the humidex and five different temperature–humidity indices (THI) were used as thermal indices. Physiological variables monitored included respiratory rate, rectal temperature, ear skin temperature and heart rate. The heat index and the humidex measuring human thermal comfort were more closely associated with physiological measures than were the ambient temperature or the THIs (in case of heat index: R2 = 0.87 for respiratory rate, R2 = 0.63 for rectal temperature, R2 = 0.70 for ear skin temperature, and R2 = 0.78 for heart rate, respectively; in case of humidex: R2 = 0.85 for respiratory rate, R2 = 0.60 for rectal temperature, R2 = 0.68 for ear skin temperature, and R2 = 0.75 for heart rate, respectively). Based on our results, parameters of human outdoor comfort seem better to estimate heat stress in dairy calves in a continental region than those of THIs or ambient temperature.

Seasonal and maternal effects on acid-base, l-lactate, electrolyte, and hematological status of 205 dairy calves born to eutocic dams

In this study, we used linear mixed models to determine the effects of season, time of sampling relative to birth (factors), duration of the delivery process, duration of maternal grooming, calf body weight (BW) at birth, and time of day (covariates) on values of venous blood gas, acid-base and electrolyte parameters, and l-lactate concentrations in dairy calves born to eutocic dams in summer (SUM, n = 101) and winter (WIN, n = 104). Neonatal vitality was assessed at 0, 1, and 24 h after delivery in a linear scoring system using muscle tone, erection of the head, muscle reflexes, heart rate, and sucking drive as criteria. Simultaneously with vitality scoring, venous blood samples were collected by jugular venipuncture. Blood was tested for pH, partial pressure of CO2 (pCO2; mmHg) and oxygen (pO2; mmHg), l-lactate (mmol/L), hemoglobin (Hb; g/L), ionized calcium (Ca2+; mmol/L), sodium (Na+; mmol/L), potassium (K+; mmol/L) and chloride (Cl-; mmol/L). Bicarbonate (HCO3-; mmol/L), base excess (BE; mmol/L), total carbon dioxide (TCO2; mmol/L), and anion gap (mmol/L) were calculated. Electrolyte parameters were affected by none of the factors or covariates. Time of day at birth did not affect any of the parameters of interest. Vitality score tended to increase over time and it showed higher values in WIN calves than in SUM calves. Concentrations of HCO3-, BE, and l-lactate indicated a higher degree of metabolic acidosis in SUM calves; however, pH was not affected by season. Concentrations of Hb were higher in SUM calves than in WIN calves; however, covariates did not affect Hb concentrations. Blood pH, concentrations of pO2, HCO3-, and BE decreased, whereas l-lactate concentrations and values of pCO2, TCO2, and anion gap increased with longer duration of delivery. A shift in acid-base balance was also linked to BW of the calf at birth, with lower values of blood pH, HCO3-, and BE in calves with higher BW compared with those with lower BW at birth, whereas TCO2 and l-lactate concentrations increased with higher calf BW at birth. Values of pO2 increased and pCO2 decreased with longer duration of maternal grooming. Blood pH, HCO3-, and BE increased, whereas l-lactate concentrations and anion gap decreased with longer duration of licking the calf. Our results indicate that prolonged delivery can impair acid-base status and can cause slight lactic acidosis, even in calves born from spontaneous or eutocic calvings, and that high BW at birth predisposes calves to acidosis. The positive effect of maternal grooming on neonatal acid-base status should be considered in parturition management. Season, duration of the delivery process, calf BW at birth, and duration of maternal grooming are recommended for consideration in future studies on blood gas and acid-base parameters in dairy calves in the immediate neonatal period.

Heart rate, heart rate variability, faecal glucocorticoid metabolites and avoidance response of dairy cows before and after changeover to an automatic milking system

The heart rate variability (HRV) parameters of dairy cows were monitored during parlour (PARL) and the later installed automatic (AMS) milking on a small-scale commercial dairy farm in Hungary. The aim of the study was to assess stress in relation to the type of milking and the frequency of human interaction. Parlour milking involved regular moving and crowding of the animals with frequent human interaction, which were much less frequent in automatic milking. The first phase of the study was conducted prior to the changeover [n = 27] and the second two months afterwards [n = 19 (of the cows from the first phase)]. Heart rate (HR) was recorded by the Polar RS800 CX recording system. HRV parameters indicative of sympathovagal balance were calculated for periods of lying and standing in the barn, waiting before milking and milking, respectively. Morning and evening faecal glucocorticoid concentrations were also measured. Fear of humans was tested by an avoidance distance test. Baseline HRV parameters showed no difference (P > 0.05) between the two systems. In the periods before, during and after milking a higher sympathetic tone was detected in cows in the PARL phase. Mean faecal glucocorticoid concentrations were higher at the time of parlour milking. The avoidance distance did not differ between the two phases. The results suggest that automatic milking might be less stressful for cows than parlour milking, possibly due to the shorter duration of restraint after milking and the less frequent human interaction.

Timing of obstetrical assistance affects peripartal cardiac autonomic function and early maternal behavior of dairy cows

Peripartal autonomic nervous system function and early maternal behavior were investigated in 79 multiparous Holstein-Friesian cows. Animals were allocated into four groups based on the technology of calving management: 1) unassisted calving in a group pen (UCG; N=19), 2) unassisted calving in an individual pen (UCI; N=21), 3) assisted calving with appropriately timed obstetrical assistance (ACA; N=20), and 4) assisted calving with premature obstetrical assistance (ACP; N=19). Heart rate, the high frequency (HF) component of heart rate variability (HRV) as a measure of vagal activity and the ratio between the low frequency (LF) and HF components (LF/HF ratio) as a parameter of sympathetic nervous system activity were calculated. Heart rate and HRV parameters were presented as areas under the curves (AUC) for the following periods: 1) prepartum period (between 96h before the onset of calving restlessness and the onset of restlessness), 2) parturition (between the onset calving restlessness and delivery), and 3) postpartum period (during a 48-h period after delivery). Pain-related behaviors were recorded during parturition (i.e., the occurrence of vocalization and stretching the neck towards the abdomen) and during a 2-h observation period after calving (i.e., the occurrence of vocalization, stretching the neck towards the abdomen and the duration of standing with an arched back). Early maternal behavior was observed during the first 2h following calving as follows: 1) latency and duration of sniffing calfs head/body, and 2) latency and duration of licking calfs head/body. No difference was found across groups in autonomic function before the onset of calving restlessness. Area under the heart rate curve was higher in ACP cows during parturition (39.6±2.5beats/min×h) compared to UCG, UCI and ACA animals (AUC=13.1±0.9beats/min×h, AUC=22.3±1.4beats/min×h and AUC=25.0±2.1beats/min×h, respectively). Area under the heart rate curve did not differ across the UCG, UCI and ACA groups during the postpartum period (AUC=65.2±16.7beats/min×h, AUC=58.0±14.2beats/min×h and AUC=62.9±12.1beats/min×h, respectively) but it was higher in ACP cows compared to the former groups (AUC=269.1±36.3beats/min×h). During parturition, area under the HF curve reflected a lower vagal tone (AUC=-30.5±1.6n.u.×h) in cows with premature obstetrical assistance than in animals that calved individually without farmer assistance (AUC=2.7±0.4n.u.×h) or with appropriately timed assistance (AUC=3.2±1.2n.u.×h). During parturition, LF/HF ratio showed greater sympathetic activity in ACP cows than in animals from any other group. Area under the HF curve was similar across UCG, UCI and ACA cows (AUC=-232.1±42.0n.u.×h, AUC=-163.4±35.6n.u.×h and AUC=-331.4±56.2n.u.×h, respectively) during the postpartum period and was the lowest in ACP cows (AUC=-1025.6±44.2n.u.×h) reflecting a long-term stress load in the latter group. During parturition, both vocalization and stretching the neck towards the abdomen occurred more often in UCG cows than in cows from any other groups, and the incidence of both behaviors was statistically higher in ACP cows than in UCI and ACA animals. There were no significant differences across groups in these behaviors during the 2-h postpartum observation. UCG cows had a shorter latency and a longer duration of maternal grooming during the first 2h following delivery compared to any other groups. UCI and ACA dams spent more time with licking the calf within the 2-h period after calving and had a shorter latency to sniff and lick the offspring compared to cows that received premature assistance. Group calving is less stressful for cows than calving in an individual pen either with or without obstetrical assistance. Calving in a group or with appropriately timed farmer assistance supports the expression of early maternal behavior and lead to a rapid postpartum recovery of the autonomic nervous system. Premature obstetrical assistance means stress for cows during parturition, leads to a prolonged postpartum recovery of the autonomic nervous system and inhibits the expression of early maternal behavior.