An experiment was carried out to study the effect of acute stress on cortisol concentration in goat milk (milk cortisol; MC) and its suitability for stress assessment. Additional variables studied were plasma cortisol (PC), blood glucose (BG), and somatic cell count (SCC). Ten goats free of mastitis at 2 mo of lactation were divided into 2 groups. One group of animals was exposed to acute stress (visual and auditory, but not physical, contact with a barking dog for 3 min) immediately before the 1000 h sampling (STR), and the other group was considered as the control group, not exposed to acute stress (CON). The animals were gradually accustomed to the sampling schedule for 1 wk before the stress treatment (pre-experimental period). The variables PC, MC, BG, SCC, and milk composition (fat, lactose, whey protein, true protein, and casein) were recorded at 0600, 1000, 1130, 1400, 1800, 2200, and 0200 h. Milk variables were recorded in both glands separately. The right gland (n=10) was completely milked and the left gland (n=10) was milked to 30 mL at every sampling except at 1000 h, when complete milking was carried out on both glands. Variables were analyzed by using a linear mixed model. Both PC and MC concentrations varied throughout the day, with values being highest in the morning. Higher PC levels were recorded in the STR group immediately after treatment compared with CON (36.9 vs 16.3 ng/mL). For MC, differences between treatments were noted 1.5h after STR treatment (1.27 vs 0.25 ng/mL). Blood glucose increased immediately after treatment in STR animals, being different from CON until 1.5h after treatment sampling (101 vs. 58 mg/dL). The SCC was not increased by STR treatment, showing higher values in the morning and afternoon compared with evening and night (5.6±0.13 to 5.87±0.13 log10 SCC). The STR treatment had no significant effect on milk composition, and overall milk yield of a complete day after stress stimulus of both groups was similar (STR: 2,067±280 g/d; CON: 2,134±427 g/d). We conclude that plasma and milk cortisol concentrations in control dairy goats varied throughout the day; MC showed significant differences in the STR group if samples were taken 1.5h after the stressing stimulus, whereas PC showed significant differences in samples taken immediately after the stressing stimulus. Additionally, MC sampling has the advantage of being noninvasive compared with blood sampling.

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Milking operations represent more than 50% of the work on a dairy ewe farm. The implementation of automatic cluster removers (ACR) is gaining popularity, as it allows the operator to avoid manual cluster detachments, simplifying the milking routines. The aim of this study was to discover the effect on the milking of Manchega ewes over an entire lactation period by using this type of devices, set up with 2 different combinations of milk flow threshold (MF) and delay time (DT) and comparing them with the traditional method using manual cluster removal. During a 15-d pre-experimental period, the animals were milked without ACR and sampling was performed to select 108 ewes and distribute them into 3 groups of similar characteristics according to their parity, milk yield, milking duration, and mammary gland sanitary status. Later, each group was milked for a duration of 4 mo in 3 different conditions: 1 with manual cluster removal, the second setting the ACR at MF 150 g/min and DT 20 s, and the third setting the ACR at MF 200 g/min and DT 10 s. Samplings of milking fraction, milking duration, milk composition, mammary gland sanitary status, teat-end status, and vacuum level in the short milk tubes during milking were performed. The use of ACR limited the vacuum drops in the short milk tubes and the edema in the teat end after milking, although no reduction in the number of new cases of mastitis was observed and the milk composition did not change. Moreover, it was noted that the use of ACR set with MF 150 g/min and DT 20 s was more efficient than the manual cluster removal, as it obtained a similar amount of extracted milk but took less time. Conversely, the use of ACR set with MF 200 g/min and DT 10 s involved a higher reduction in individual milking duration and the milking duration of groups of animals but reduced milk extracted.