Background: Machine milking can induce both physical and psychological stimuli, with physiological adjustments, including adrenocortical, haematochemical and haematological changes, particularly in dairy farms. The purpose of the present study was to evaluate the physiological patterns of cortisol responses and total protein and haematocrit changes in pregnant dairy cows before and after morning and early afternoon machine milking, by taking into account the effect of different milking times and breed. Materials, Methods & Results: This was a comparative and observational study on the adaptive responses of circulating cortisol concentrations, total protein and haematocrit values to machine milking evaluated in 36 healthy multiparous lactating dairy cows, 5.2 ± 2.54 years of age, at the 4th-5th month of pregnancy, stabled in stall. The animals were divided in three groups according to different breed (group A: 10 Holstein Friesian dairy cows; group B: 10 Swedish Red dairy cows; group C: 16 crossbred (Friesian-cross) dairy cows and were submitted to machine milking 2 times daily at 06:30 a.m. and at 03:30 p.m. Blood samples were collected via the coccygeal vessels in the tail, in the morning: in baseline conditions (before milking) at 06:00 a.m., and after milking at 07:00 a.m.; and in the early afternoon: in baseline conditions, at 03:00 a.m., and after milking at 04:00 p.m. for two consecutive days. One-way RM ANOVA showed significant effects of the machine milking on the cortisol (F=29.66 and F=11.50; P < 0.001), total protein (F=27.24 and F=30.34; P < 0.001) and haematocrit (F=19.44 and F=13.50; P < 0.01) changes in Holstein Friesian dairy cows, both at morning and at afternoon. Conversely, no significant effects of the milking were observed in Swedish Red and Crossbreed dairy cows on cortisol changes, but only for total protein (F=7.69 and F=14.20; P < 0.01) and haematocrit (F=18.12 and F=12.11; P < 0.01) changes for group B, and for total protein (F=12.21 and F=19.11; P < 0.01) and haematocrit (F=16.21 and F=21.15; P < 0.01) changes for group C, respectively. Discussion: Data obtained showed a similar biphasic adrenocortical response of all three groups of lactating dairy cows depending on milking times, with higher cortisol concentration in the morning than in the afternoon, irrespective of different breed. Moreover, the results confirmed that the degree of the coping capacity towards the new milking environment varies widely among cows of different breeds, as showed by significant differences described among the Holstein Friesian, Swedish Red and crossbred dairy cows along time. The similar pattern of total protein, characterized by a general increase after morning and afternoon milking confirmed the physiological transfer of amino acid from rumen to milk. The superimposable Hct trend, characterized by a general decrease after morning and afternoon milking, confirmed the hypothesis that physiological dehydration state occurred after milking in dairy cows. The significant and fluctuating involvement of total protein and haematocrit changes after machine milking could be due to metabolic stimuli associated to physiological dehydration and productive performances. The highly dynamic patterns of the homeostatic mechanisms involved and activated during machine milking made it difficult to deduce any simple relationship between different breed and milking times in dairy cows.

Machine milking impact on dairy cows’ physiological adjustment: an observational approach according to different breed

FAZIO, Esterina;MEDICA, Pietro;CRAVANA, CRISTINA;FERLAZZO, Adriana
2015-01-01

Abstract

Background: Machine milking can induce both physical and psychological stimuli, with physiological adjustments, including adrenocortical, haematochemical and haematological changes, particularly in dairy farms. The purpose of the present study was to evaluate the physiological patterns of cortisol responses and total protein and haematocrit changes in pregnant dairy cows before and after morning and early afternoon machine milking, by taking into account the effect of different milking times and breed. Materials, Methods & Results: This was a comparative and observational study on the adaptive responses of circulating cortisol concentrations, total protein and haematocrit values to machine milking evaluated in 36 healthy multiparous lactating dairy cows, 5.2 ± 2.54 years of age, at the 4th-5th month of pregnancy, stabled in stall. The animals were divided in three groups according to different breed (group A: 10 Holstein Friesian dairy cows; group B: 10 Swedish Red dairy cows; group C: 16 crossbred (Friesian-cross) dairy cows and were submitted to machine milking 2 times daily at 06:30 a.m. and at 03:30 p.m. Blood samples were collected via the coccygeal vessels in the tail, in the morning: in baseline conditions (before milking) at 06:00 a.m., and after milking at 07:00 a.m.; and in the early afternoon: in baseline conditions, at 03:00 a.m., and after milking at 04:00 p.m. for two consecutive days. One-way RM ANOVA showed significant effects of the machine milking on the cortisol (F=29.66 and F=11.50; P < 0.001), total protein (F=27.24 and F=30.34; P < 0.001) and haematocrit (F=19.44 and F=13.50; P < 0.01) changes in Holstein Friesian dairy cows, both at morning and at afternoon. Conversely, no significant effects of the milking were observed in Swedish Red and Crossbreed dairy cows on cortisol changes, but only for total protein (F=7.69 and F=14.20; P < 0.01) and haematocrit (F=18.12 and F=12.11; P < 0.01) changes for group B, and for total protein (F=12.21 and F=19.11; P < 0.01) and haematocrit (F=16.21 and F=21.15; P < 0.01) changes for group C, respectively. Discussion: Data obtained showed a similar biphasic adrenocortical response of all three groups of lactating dairy cows depending on milking times, with higher cortisol concentration in the morning than in the afternoon, irrespective of different breed. Moreover, the results confirmed that the degree of the coping capacity towards the new milking environment varies widely among cows of different breeds, as showed by significant differences described among the Holstein Friesian, Swedish Red and crossbred dairy cows along time. The similar pattern of total protein, characterized by a general increase after morning and afternoon milking confirmed the physiological transfer of amino acid from rumen to milk. The superimposable Hct trend, characterized by a general decrease after morning and afternoon milking, confirmed the hypothesis that physiological dehydration state occurred after milking in dairy cows. The significant and fluctuating involvement of total protein and haematocrit changes after machine milking could be due to metabolic stimuli associated to physiological dehydration and productive performances. The highly dynamic patterns of the homeostatic mechanisms involved and activated during machine milking made it difficult to deduce any simple relationship between different breed and milking times in dairy cows.
2015
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/3063025
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