Pregnancy challenges the homeostatic mechanisms of the mammalian body, especially these controlling the cardiovascular system. In the dairy ruminant the lactation period places the same or even greater demands on that system, but the adaptations that help dairy goats to deal with its demanding lactation period have received comparatively little attention. In goats, the blood volume expands in parallel with the body weight increase during pregnancy and with an increase in cardiac output and a decrease in total peripheral resistance. In a study by Linzell (1974), the cardiac output remained at the same level or became greater after parturition, and Chaiyabutr et al. (1980 a,b) have reported that lactating goats with low milk production had a smaller cardiac output.The blood flow to the mammary gland is directly related to milk production (Linzell, 1974;Davis & Collier, 1985), and with the increasing efficiency of milk production in dairy goats and cows it appeared of interest to study the effect on cardiac dimensions and function in the dairy goat. For cardiovascular studies during different reproductive periods it is preferable to use the same animals, but no serial studies on heart dimensions and function have previously been done in goats. Echocardiography is a non-invasive method for measuring stroke volume and cardiac output from cardiac dimensions and heart rate. It has been claimed to be the method of choice for serial measurements in pregnant women (Duvekot & Peeters, 1994). It has also been evaluated in clinically normal cows (Pipers et al. 1978) and is used routinely for cardiac diagnosis in many species, including goats (Yamaga & Too, 1984;Gardner et al. 1992). We studied cardiac dimensions and function during late pregnancy, peak lactation, and the non-pregnant, non-lactating (dry) period in dairy goats. Chronically implanted telemetric devices were used for measurements of arterial blood pressure (Hydbring et al. 1997) in order to calculate changes in total peripheral resistance (TPR) and to investigate if the echocardiographic procedure affected the goats.A serial study of heart function during pregnancy, lactation and the dry period in dairy goats using echocardiography Echocardiography and Doppler measurements were performed to investigate changes in heart dimensions and function during pregnancy, lactation and the non-pregnant, non-lactating (dry) period in dairy goats. Eight Swedish domestic goats (Capra hircus) were studied with two-dimensional (2DE), M-mode and continuous wave Doppler measurements. Cardiac dimensions did not differ between periods. The mean cardiac outputs were 35 and 28 % greater during pregnancy and lactation, respectively, vs. the dry period. Arterial blood pressure (measured by telemetry) did not differ between reproductive periods before echocardiographic measurements, but became elevated during the measurements, with the smallest rise during lactation. Heart rate was elevated during pregnancy and increased further during echocardiographic measurements, but was not elevat...

BackgroundSuckling can be a peaceful or vulnerable event for goats and kids, whereas, separation is suggested as stressful. The aim of this study was to investigate physiology and behaviour in these two different situations in dairy goats.MethodsFour studies were performed with seven goats kept with their first-born kid in individual boxes. The goats were videotaped and heart rate and arterial blood pressure were recorded every minute by telemetry from parturition until 24 hours after separation. One to two days after parturition, Study 1 was performed with analyses of heart rate and blood pressure around a suckling. In Study 2, performed 3-5 days after parturition, blood sampling was done before, during and after suckling. Study 3 was performed 4-6 days post partum, with blood sampling before and after a permanent goat and kid separation. In addition, vocalisations were recorded after separation. Blood samples were obtained from a jugular vein catheter and analysed for plasma cortisol, β-endorphin, oxytocin, and vasopressin concentrations. Study 4 was performed during the first (N1) and second nights (N2) after parturition and the nights after Study 2 (N3) and 3 (N4). Heart rate, blood pressure and time spent lying down were recorded.ResultsThe kids suckled 2 ± 0.2 times per hour and each suckling bout lasted 43 ± 15 s. In Study 1, heart rate and blood pressure did not change significantly during undisturbed suckling. In Study 2, plasma cortisol (P ≤ 0.05 during suckling and P ≤ 0.01 five minutes after suckling) and β-endorphin (P ≤ 0.05) concentrations increased during suckling, but oxytocin and vasopressin concentrations did not change. In Study 3, the goats and kids vocalised intensively during the first 20 minutes after separation, but the physiological variables were not affected. In Study 4, heart rate and arterial blood pressure declined gradually after parturition and were lowest during N4 (P ≤ 0.05) when the goats spent longer time lying down than during earlier nights (P ≤ 0.01 during N1 and N3 and P ≤ 0.05 during N2).ConclusionsSuckling elevated plasma cortisol and β-endorphin concentrations in the goats. The intensive vocalisation in the goats after separation, earlier suggested to indicate stress, was not accompanied by cardiovascular or endocrine responses.

The aim of the study was to examine how early permanent separation, separation during the day only, or full-time access to the mother goat affected goat kids during social isolation with a sudden sound of a dog bark at two weeks and two months, and a novel arena test with a novel object at two months. Kids permanently separated reduced their vocalization earlier and had a higher heart rate before and after dog bark during isolation at two weeks, no effect was found on the daytime separated kids. Daytime separated kids bleated more at two weeks and decreased heart rate after dog barking at two months. Daytime separated kids showed the strongest fear reaction in the arena test, no effect was found on the permanently separated kids. Kids separated early vocalized more before novel object and showed more explorative behavior afterwards. Our study shows different responses in goat kids separated early permanent, daytime separated, or kept full-time with mother, which demonstrates the importance of if and how the mother is present, and the impact of using a wide variety of physiological and behavioral measures when evaluating stress in animal welfare research.

We address the hypothesis that keeping kids and mothers together would have positive effects on the milk composition of the mother and the behaviour of the kids. Kids were either permanently separated (SEP), daily separated between 7.30 and 15 h (DAY-SEP) or kept with mothers 24 h/d (NON-SEP). The NON-SEP kids were only allowed to suckle one teat. All kids had similar growth rate throughout the study (lactation days 5–70). DAY-SEP kids spent 24% of their time with their mother at both ages. NON-SEP spent only 15% of the time with their mothers at 2 weeks of age and this increased to 28% at 2 months of age. NON-SEP kids showed more hiding behaviour at 2 weeks and SEP were more active alone, at both 2 weeks and 2 months, compared to the other treatments. The mean available milk yield and fat concentration were higher in DAY-SEP goats (2420 g ± 119 g and 4.9 ± 0.1%) compared with NON-SEP goats (2149 ± 79 g and 4.4 ± 0.1%). There were no differences between DAY-SEP and NON-SEP goats in total protein, lactose, or casein concentrations. Based on these data it was estimated that 7.1 kg milk was needed to produce 1 kg semi-hard cheese in DAY-SEP goats and 7.5 kg in NON-SEP goats, respectively. When comparing milk yield and composition between udder halves, the milk yield was, as expected, higher from the machine milked teat than from the suckled one in the NON-SEP goats but there was no difference between right and left udder halves in DAY-SEP goats. Milk fat concentration varied between teats at morning and afternoon milkings in NON-SEP goats, but there was no difference in milk fat between udder-halves in DAY-SEP goats. In conclusion, the kid growth rate was similar in all treatments, however, an altered behaviour was seen in permanently separated kids (SEP). The results show that it is possible to have a high milk yield and fat concentration with one kid together with the dam.

The purpose of this study was to assess the diversity of physiological stress responses elicited by tethering versus loose holding in the Swedish domestic goat (Capra hircus). Eight goats were randomly divided into two groups and the experiment was performed in a crossover design. Six goats had implanted transmitters that registered heart rate and arterial blood pressure telemetrically and blood samples were taken on separate days. Heart rate increased around feeding both when the goats were held loose in pairs, and when they were tied up. When the goats were tethered, the heart rates and blood pressures were higher, and the concentrations of β-endorphin and oxytocin lower, compared to when held loose in pairs. In conclusion, housing and the company of another animal affect arterial blood pressure, heart rate, and the concentrations of β-endorphin and oxytocin in goats, but the cortisol and vasopressin concentrations did not differ between the treatments. The higher arterial blood pressure and heart rate, and lower concentrations of β-endorphin and oxytocin in tethered goats indicate that being tied up may be more stressful for the goats compared to being held loose. The use of single measures, eg cortisol concentrations, was not sufficient to give an accurate picture of the animals' response to the management system. This study demonstrates the importance of using a wide variety of physiological measures when evaluating stress in animal welfare research.