Competition for oestrous ewes between rams reared by their mothers or artificially reared: Effects on sexual behaviour and testosterone and cortisol serum concentrations

The objective of this study was to determine how the social competition for an oestrous ewe affects the sexual behaviour and the endocrine response in two groups of rams, one reared by their mothers and another artificially reared. Thus, we compared the sexual behaviour and testosterone and cortisol changes in each group of rams in competitive and non-competitive tests, both during the first and second breeding seasons. Two groups of rams were: 1) artificially reared lambs, separated from their dams 24-36 h after birth (Week 0) and artificially fed with sheep milk until 10 weeks of age (group AR, n = 14); and 2) lambs reared by their dams until 10 weeks of age (group DR, n = 13). Rams were subjected to non-competitive and competitive tests for an oestrous ewe during their first and second breeding seasons, when they were 8 and 20 months old, respectively. Sexual behaviours toward an oestrous ewe were recorded during 20 min and the testosterone and cortisol concentrations were determined in serum samples collected immediately before the test, and 20, 40 and 60 min after it. During the first breeding season, the number of flehmen decreased in DR rams, and the number of flehmen and ano-genital sniffings also decreased in DR rams, but the frequency of some copulatory behaviours increased (matings and ejaculation/total mounts in DR rams, and total mounts in AR rams) in competitive tests. During the second breeding season, competition caused a decrease in the number of all the recorded behaviours (courtship and copulation) with the exception of flehmen in AR rams; however, in DR rams only the number of the copulatory behaviours decreased under competition. Competition did not affect the endocrine response during the first breeding season. During the second breeding season, while testosterone concentrations were greater in non-competitive than in competitive tests at 60 min (P = 0.0008) in AR rams, in DR rams it tended to be greater (P = 0.09). Competition did not affect cortisol concentrations in any group or season, but in all tests the concentrations increased at the end of the test (P < 0.05). In conclusion, the lack of the mother during rearing negatively affected the sexual motivation and the testosterone response of rams to oestrous ewes in competitive tests, effects that were more evident when adults. Neither the absence of the mother during rearing nor competition for oestrous ewes affected the stress response (evidenced by increase in cortisol concentration) in rams during both seasons.

Ejaculation does not contribute to the stress response to electroejaculation in sheep

Electroejaculation procedures (EEPs) provoke stress; nevertheless, ejaculation produces physiological changes similar as those usually used to measure stress responses. The application of EEP to animals that cannot ejaculate-as ewes-may be useful to discriminate the responses induced by ejaculation from those provoked by EEP. The aim was to determine the stress response to EEP in rams and ewes. The EEPs were applied to 10 rams and 10 ewes during the non-breeding season, and the number of vocalizations, the heart rate, rectal temperature, serum cortisol concentration, biochemical and haematological parameters were measured. Overall, EEP provoked increases in cortisol concentration, glycaemia, rectal temperature and concentration of creatine kinase (all them: p < .0001) as well as relative concentration of granulocytes (p = .003) and absolute granulocyte concentration (p = .0002) in both, rams and ewes. Heart rate, relative concentration of lymphocytes (p = .001), haematocrit (p = .02) and haemoglobin (p = .045) decreased in animals from both genders after EEP. Besides, cortisol (p < .0001), rectal temperature (p = .002) and glycaemia (p = .001) were greater in ewes than rams, and creatine kinase also tended to be greater in ewes than rams (p = .054). On the other hand, the number of animals that vocalized (p = .006), white blood cells (p = .02) and absolute lymphocytes (p = .02) were greater in rams than ewes. The general trends show a similar pattern of stress responses in animals from both genders. Therefore, we concluded that ejaculation does not contribute to the stress response provoked by the EEP. This procedure also provokes muscular damage and probably pain.

Behavioural response of grazing lambs to changes associated with feeding and separation from their mothers at weaning

This study aimed to determine which behaviours were provoked in lambs in response to the separation from their dams or to the changes associated with feeding and separation from adults at weaning. Fourteen lambs were separated from their dams at 24-36 h after birth and artificially reared (AR) in presence of four adult ewes, while another 13 lambs remained with their dams from birth (DR). At 75 days of age on average (day 0) DR lambs were separated from their dams and AR lambs no longer received sheep's milk and were separated from adults. Behaviours were recorded every 10 min (6h per day) from day -3 to day 4. We observed an increase (p<0.05) in pacing behaviour, as well as in the frequency in which lambs were observed vocalizing, walking and staying under shade, and a decrease (p<0.05) in the frequency of grazing in the DR group in comparison to AR at weaning, but there were no differences in body weight gain from day -4 to day 5 after weaning. Additionally, we observed a decrease in the frequency in which lambs were observed standing and grazing (p<0.05), and an increase in vocalizing and staying under shade (p<0.05) in group AR at weaning in comparison to the previous days. Therefore, it was concluded that although some specific behaviours as pacing or vocalizing were clearly related with the separation from the mother at weaning, the change of food and separation from adults must be also considered as an important stressor in grazing lambs at weaning. In addition, the provision of shade when grazing is also important for lambs at the time of weaning.

Milk casein and fatty acid fractions in early lactation are affected by nutritional regulation of body condition score at the beginning of the transition period in primiparous and multiparous cows under grazing conditions

The objective was to evaluate the effect of body condition score (BCS) at 30 days before calving (-30 days) induced by a differential nutritional management, parity and week of lactation (WOL) on milk yield and composition, and milk casein and fatty acid composition. Primiparous and multiparous Holstein cows with high BCS (PH, n = 13; MH, n = 9) and low BCS (PL, n = 9; ML = 8) under grazing conditions were sampled at WOL 2 and 8 (before and after peak of lactation). Milk yield was greater in multiparous than in primiparous cows and tended to decrease from WOL 2 to 8 only in ML cows. Milk protein, fat and casein yields were greater in multiparous than in primiparous cows and decreased from WOL 2 to 8. Milk casein concentration in milk protein was greater in MH cows than in ML, PH and PL cows at WOL 2. Milk κ-casein was greater, and β-casein was less in multiparous than in primiparous cows. As lactation progressed, proportion of casein fractions were not altered. Only κ-casein fraction was affected by BCS at -30 days as PL showed a higher concentration than PH. The de novo (4:0-15:1) and mixed-origin fatty acids (16:0-16:1) in milk fat increased, whereas preformed fatty acids (≥17:0) decreased from WOL 2 to 8. Saturated (SAT) fatty acids tended to be greater and monounsaturated fatty acids (MUFA) were less in multiparous than in primiparous cows. High-BCS cows had greater concentrations of polyunsaturated (PUFA), conjugated linoleic acid (CLA) as well as n-6 and n-3 fatty acids in milk fat than low-BCS cows. The results indicate that casein and fatty acid fractions in milk were affected by parity and may be modified by a differential nutritional management during the pre-calving period (BCS at -30 days) in cows under grazing conditions.

The stress response of frequently electroejaculated rams to electroejaculation: hormonal, physiological, biochemical, haematological and behavioural parameters

Electroejaculation (EE) is a technique widely used to collect semen in ruminants, which produces a stress response with negative effects on animal welfare. The aim of this paper was to characterize the stress response during conventional EE in rams that have been frequently electroejaculated. Blood samples were collected since 20 min before and until 120 min after electroejaculating 10 rams. Electroejaculation affected hormone concentration, as cortisol increased, and testosterone decreased after EE. Heart and respiratory rate increased 10 min after EE. Several blood parameters, such as glycaemia, an increase in total protein and creatine kinase concentrations and a decrease in haematocrit, haemoglobin, red blood cell and alkaline phosphatase concentrations. The rams vocalized 13.8 ± 2.4 times, and the largest length of vocalizations during EE was associated with the numbers of pulses in which the rams ejaculated. In this paper, we provide a complete characterization of the stress response to EE in rams. We showed that although rams have been frequently electroejaculated, an important stress response including changes in respiratory rate, testosterone concentrations, haematological and biochemical parameters were observed, besides the changes in cortisol concentrations and heart rate, suggesting that rams were not habituated to EE. In addition, we described the main parameters of vocalizations and its relation with the moment of EE. The information displayed on the frequent use of EE in the rams should be considered in relation to the welfare implications.

Female effect on antlers of pampas deer (Ozotoceros bezoarticus)

Size and bone mineralization of deer antlers are related to testosterone concentrations, and antler cast is observed after withdrawal of testosterone concentration. Our objectives were to determine if (i) contact with hinds stimulates antler development and increases hard antler period length in pampas deer ( Ozotoceros bezoarticus (L., 1758)) and (ii) antlers from males that were or were not in contact with hinds differ in colour. While 5 males were in breeding paddocks consisting of 1 adult stag and 5–10 hinds, the other 6 males were allocated as a single-male group. We collected, weighed, and measured the volume, circumferences, and lengths of antlers, and determined their colour. First antler cast tended to be later in males in contact with females than those in the single-male group. Antler mass and volume were greater in antlers from males in contact with females. Circumference at the base of first and second tines was also greater in antlers collected from males in contact with females. Surfaces of antlers from these males were darker than those of antlers from males that remained isolated from females in all points. Hind contact stimulated male pampas deer, increasing antler mass, size, and darkness, as well as possibly hard antler period length.

Influence of estrus of dairy goats on somatic cell count, milk traits, and sex steroid receptors in the mammary gland

Two experiments were conducted to study the effect of the stage of a spontaneous estrus cycle on milk yield and constituents [somatic cell count (SCC), fat, protein, caseins, lactose, and urea content] and on estrogen receptor-alpha (ERalpha ) and progesterone receptor (PR) immunostaining in the mammary gland. In experiment I, the major components of milk and SCC were monitored weekly in 80 lactating Saanen goats for 6 wk, whereas detection of estrus was daily. In experiment II, milk samples were collected daily for SCC determination during 1 spontaneous estrus (d 0) until the second spontaneous estrus in 14 Saanen goats. The day of the estrous cycle was confirmed by plasma progesterone and 17beta-estradiol levels. Immunoreactivity of ERalpha and PR was analyzed in mammary gland samples of 8 Saanen goats (d 0, n = 4; d 10, n = 4) and the number of positive nuclei and intensity of the staining were evaluated in 1,000 cells. In experiment I, milk casein and protein percentages were significantly affected by the stage of estrous cycle; during proestrus and estrus, these variables were higher (3.32 +/- 0.06 and 4.44 +/- 0.08) than during metestrus (3.03 +/- 0.07 and 4.07 +/- 0.10), but not higher than during diestrus (3.23 +/- 0.06 and 4.35 +/- 0.09, respectively). In experiment II, daily measurement of SCC revealed higher levels at estrus (7,195 +/- 672 x 10(3) cells/mL) and a decline toward the luteal phase (1,694 +/- 672 +/- 10(3) cells/mL). Estrogen receptor-alpha and PR immunostaining were exclusively detected on epithelial cells. The percentage of positive nuclei to ERalpha was higher on d 0 than on d 10 (75.4 +/- 8.8 vs. 68.3 +/- 8.8%), but no change was observed for PR (4.0 +/- 0.3 vs. 3.5 +/- 0.4%). The average immunostaining intensity for both receptors was greater on d 0 than on d 10 (ERalpha : 1.44 +/- 0.02 vs. 1.35 +/- 0.02; PR: 0.079 +/- 0.008 vs. 0.057 +/- 0.008). The high SCC at estrus in experiment II was associated with high plasma estradiol and low progesterone, suggesting that the increased SCC could be brought about by the estrogen-induced proliferation and exfoliation of epithelial cells. In addition, this action may be supported by the higher sensitivity to estrogens (ERalpha content) found at d 0.