Mixing at the beginning of fattening moderates social buffering in beef bulls

Cattle establish strong preferential associations early in their life that determine the cohesiveness within a group and can diminish fear responses (i.e. social buffering). Mixing beef bulls at the beginning of fattening may lead to less cohesiveness. Moreover, mixing beef bulls induces aggressive interactions, especially when the bulls are of similar weights. This study was aimed at evaluating the cohesiveness and fear responses of 64 bulls that were either mixed versus unmixed and of homogeneous vs. heterogeneous body weights (2 × 2 factorial design, four groups of four bulls each per treatment). Social cohesiveness was assessed during food competition and a social separation test. Fear responses were observed during the social separation test and pre-slaughter handling. During food competition, unmixed bulls exchanged more non-agonistic interactions (P < 0.05) and were more tolerant with each other than mixed bulls (time spent eating: P < 0.05). Unmixed bulls displayed less fear responses during physical separation (elimination: P < 0.05; startle: P < 0.01) and were less stressed by pre-slaughter handling (blood cortisol: P < 0.05). Very few effects could be attributed to the homogeneity of weights within groups. It is concluded that mixing bulls at the beginning of fattening reduces the strength of positive social relationships and renders social buffering less effective during subsequent fattening. We recommend maintaining familiar bulls together throughout fattening in order to preserve cohesiveness within groups and for animals to benefit from social buffering during stressful situations.     

Proliferation and apoptosis in subcutaneous adipose tissue of lactating cows with different genetic merit for milk yield

The aim of this study was to investigate the adipocyte size and fate in subcutaneous fat (scAT) of cows diverging for genetic merit at mid lactation stage, when anabolic activity increases and animals are in a state of positive energy balance. Twenty mid lactation cows (180 ± 20 days in milk) grouped according to the Estimated Breeding Values (EBV) for milk yield in plus (EBVp) and minus (EBVm) variants were selected. Average of adipocytes area, proliferation and apoptotic labelling index as well as DLK-1 expression, a marker of pre-adipocytes, were immunohistochemically evaluated in scAT biopsies. In EBVp cows, the BCS was lower (P < 0.01) whereas milk yield, protein, fat yield (P < 0.001) and plasma free fatty acid concentration (P < 0.05) were higher. The scAT of EBVp cows showed a significantly (P < 0.001) higher frequency between 500 and 3000 μm² classes in comparison to EBVm cows, that showed a significantly (P < 0.01) higher apoptotic labeling index. The immunohistochemical reaction showed DLK-1 positivity in scAT of EBVp cows. Taking together, the data indicate a link between milk yield genetic merit of cows, scAT morphology and function, suggesting greater dynamics and metabolic flexibility in EBVp cows.     

Comparison of the behaviour of Awassi lambs in cafeteria feeding system with single diet feeding system

This study was carried out to compare behavioural activities of Awassi lambs in cafeteria feeding system with conventional feeding (control) that animals fed concentrate. Sixteen, 3-month-old male lambs were housed individually for 42 days. The main effect was on the feeding systems, cafeteria and control. Cafeteria lambs (n=8) were offered the main ingredients (barley, cotton seed meal (CSM), wheat bran and alfalfa straw), while control animals (n=8) were fed a single diet (48% barley, 22% cottonseed meal, 18% wheat bran, 10% alfalfa and 2% vitamin–mineral mixture; having 2467 Kcal ME and 161 g kg⁻¹) with the same main ingredients with slightly higher nutrient content for growth. Food and water intakes were recorded daily, while behavioural observations were recorded twice a week for a period of 1 h at 5 min intervals at 13:00, 16:00, 19:00, 22:00, 01:00, 04:00, 07:00 and 10:00 h after the initiation of daily feeding. After every 5 min, each lamb was monitored to determine its eating, ruminating, drinking, walking, standing, playing, resting and other activities.Cafeteria lambs selected a diet that matched their growth requirement as did control lambs. However, cafeteria lambs ate more (P<0.01). Cafeteria animals preferred cotton seed meal (42.4%) to barley (32.9%) without changing their water intake, final live weight and daily gain (P>0.05). Cafeteria lambs also had higher rates of eating (22% versus 19%, P<0.01), ruminating (24% versus 23%, P>0.05) and resting (29% versus 23%, P<0.01) than the control lambs. On the other hand, cafeteria lambs spent less time standing (19% versus 25%, P<0.01) and walking (1.5% versus 2.1%, P<0.01) compared with control animals. In conclusion, cafeteria lambs selected a diet that matched their presumed biological (behavioral and nutritional) needs without changing their growth performance.     

Feeding soybean meal increases the blood level of isoflavones and reduces the steroidogenic capacity in bovine corpora lutea,without affecting peripheral progesterone concentrations

Thirty-three Holstein-Friesian cows were followed from 14 days pre partum until the fourth ovulation post partum. Housing conditions and basic ration were identical for all animals. Concentrates were individually supplemented according to the daily milk production level, using two different types of protein rich concentrates: soybean meal and rapeseed meal. Soybean and rapeseed meal are known to be respectively high and low in isoflavones. Cows were randomly divided into three groups and blocked for parity. Group I (n = 11) was supplemented with soybean meal and acted as control group. Groups II (n = 11) and III (n = 11) were respectively supplemented with soybean and rapeseed meal and were subjected to a biopsy sampling of the corpus luteum at day 9 of the first three postpartal estrous cycles.Soybean meal supplementation to lactating dairy cows (1.72 kg on average) induced an increase in the blood concentration of equol, dihydrodaidzein, o-desmethylangolensin in both soy groups and resulted in a reduced area occupied by steroidogenic (P = 0.012) and endothelial cells (P = 0.0007) in the luteal biopsies. Blood concentrations of equol and glycitein were negatively correlated with the areas occupied by steroidogenic (r = −0.410 with P = 0.0002, respectively r = −0.351 with P = 0.008) and endothelial cells (r = −0.337 with P = 0.01, respectively r = −0.233 with P = 0.085) in the 3 first estrous cycles. The latter however did not affect the diestrous peripheral blood progesterone concentration.     

Evaluation of on-farm methods for testing the human–animal relationship in dairy herds with cubicle loose housing systems—test–retest and inter-observer reliability and consistency to familiarity of test person

The human–animal relationship is an important factor when considering animal welfare at herd level. In the present study, two behavioural tests for the on-farm assessment of the human–animal relationship at herd level of dairy cows housed in loose housing cubicle systems were evaluated with respect to inter-observer reliability, test–retest reliability, effect of familiarity of test person as well as inter-correlation of the two tests. In a voluntary animal approach (VAA) test, the number of cows and the latencies to approach and touch a stationary test person was measured. In an avoidance (AV) test, the cows’ avoidance reactions to an approaching test person were categorised. A first study was carried out in 12 commercial Danish and Austrian dairy farms. On each farm, both behaviour tests were carried out on the same day and repeated within 4–5 days. For each test, cows were tested by both an unfamiliar and a familiar test person (the stock-person) and two observers simultaneously registered the animals’ test responses. The inter-observer reliability of both behavioural tests was found to be high (VAA: 2.5-m approach r=0.98 (P<0.001) and touch r=0.97 (P<0.001); AV: Kappa coefficient_weighted=0.886 (prevalence index for flight distance≥2 m is 0.636)). The cows at herd level showed shortest latency for touching an unfamiliar test person on the first test day (P=0.006). Further, the AV test had a high test–retest reliability (Kappa coefficient_weighted=0.503 (prevalence index for flight distance≥2 m is −0.660)) and results indicated no effect of familiarity of test person (Kappa coefficient_weighted=0.463 (prevalence index for flight distance≥2 m is −0.677)). In a second study, the correlation between the two behavioural tests (similar measures) was evaluated. On each of 10 commercial Danish dairy farms with loose housing cubicle systems at four repeated sessions, both behaviour tests were carried out on the same day. For each test cows were tested by the stock-person. The VAA and AV tests at herd level were highly correlated (r_s=−0.84; P=0.002).The results suggest that the AV test is valid and applicable for on-farm assessment of the human–animal relationship at herd level. This accounts only partly for the VAA test, which seem to be more unclear regarding motivation for the animals’ approach behaviour.     

The effect of prostaglandin F(2α) administration at the time of insemination on the pregnancy rate of dairy cows

This paper addresses the question whether the pregnancy rate of dairy cows and heifers may be affected by administering prostaglandin F_2α at the time of artificial insemination. A field trial involving 1031 dairy cows and heifers distributed to a large number of small dairy farms in an area of extensive farming in central Germany provided evidence that intramuscular administration of 25 mg Dinoprost (Dinolytic^®) at the time of insemination has no effect on pregnancy rate (61% of the cows and heifers were pregnant in both prostaglandin F_2α-treated and saline control groups). On the other hand, deposition of 0.5 mL of a 0.5 mg/mL Dinoprost solution in the uterine lumen immediately after artificial insemination gave rise to a pregnancy rate of 66% as compared with 59% in saline controls. The increase in pregnancy rate of 229 prostaglandin F_2α-treated animals (66% pregnant) over that of 226 saline controls (59% pregnant) amounted to 12%. This improvement was not statistically significant (P = 0.12). Factors exerting a significant effect on pregnancy rate were parity (74% pregnancies in heifers versus 57% in cows, P < 0.01 and 65% pregnancies in first parity-cows versus 55% in older cows, P < 0.01) and season (57% during the barn season versus 64% during the pasture season, P < 0.05), whereas length of service period, level of milk production and serum or milk progesterone level at the time of insemination did not. A follow-up trial involving more animals will have to be conducted aimed at confirming the promising results obtained by intrauterine PGF_2α administration.     

Increasing the interval between winter outdoor exercise aggravates agonistic interactions in Hérens cows kept in tie-stalls

Cows of the dual-purpose Hérens breed are highly motivated to engage in dominance interactions and thus famous for the cow fights traditionally organised by Swiss breeders. However, this characteristic may result in excessively aggressive behaviour when cows kept in tie-stalls meet during winter outdoor exercise. This can be dangerous for both animals and breeders in terms of likelihood of injury. Regular outdoor exercise is important for the health and social behaviour of cows, and is mandatory in Switzerland. The aim of this study was to find the maximum interval between two exercise days that leads to a minimum of agonistic interactions between the cows.The study was conducted with 51 horned Hérens cows kept on six Swiss working farms. The length of the interval between days with winter outdoor exercise (daily, every third, fourth or fifth day) was experimentally increased on each farm. At the beginning of the experiment, information on social parameters (dominance index and dominance index difference) was collected for each animal and dyad. During the first 40 min of each exercise period (divided into four time-blocks of 10 min each), agonistic and allogrooming behaviour were recorded for each cow. In order to evaluate the risk of injury, all fresh wounds were noted after each exercise period, with three body parts (head, udder, rest of body) being differentiated. All data were analysed using linear mixed-effects models.The frequency of agonistic interactions increased along with the interval between two days of exercise (p < 0.001), and decreased in the course of the exercise on a given day (p < 0.001). The duration of fights increased if the interval between exercise was longer than three days. The frequency of agonistic interactions without body contact increased along with the increasing dominance index of the actor cow (from the omega to the alpha animal, p < 0.001), and, at the same time, the proportion of agonistic interactions with body contact decreased with increasing difference in dominance index between the interacting cows (p < 0.001). The risk of injury to the udder and the body (except for the head) also increased along with an increasing interval between exercise periods (udder: p < 0.001; body: p < 0.001).In conclusion, cows of the Hérens breed show pronounced agonistic behaviour after only a few days of tethering in comparison with cows who have daily winter outdoor exercise. Based on our results, the length of the interval between exercise days should be as short as possible, and in any case not longer than three days.     

Postpartum resumption of ovarian cycling activity in first-calf suckled beef cows exposed to familiar or unfamiliar bulls

The objective of this experiment was to determine if the proportion of first-calf suckled beef cows that resumed ovulatory cycles and the interval to resumption of ovarian cycling activity differ after exposure to either “unfamiliar” bulls or cows on d 35 postpartum, after exposure to either “familiar” bulls or cows for the first 30–32 d after calving. Fifty Angus × Hereford cows were stratified by calving date, calf BW, and calf sex by d 3 postpartum, and assigned to be exposed to familiar epididectomized bulls (BEF; n = 25) or familiar mature ovariectomized (OVX) cows (CEF; n = 25). On d 35 after calving, 12 BEF cows were assigned to be exposed to unfamiliar bulls (BEU); likewise, 12 CEF cows were assigned to be exposed to unfamiliar OVX cows (CEU). Cows were in their treatments for either 95 d (BEF and CEF) or 60 d (BEU and CEU) during the experiment. Blood samples were collected every third d from the beginning to the end of the experiment. A rise in progesterone concentration of >0.5 ng/mL in consecutive samples was used as the criterion for resumption of ovulatory cycles. Exposing cows to bulls on d 5 after calving and then switching a subset of these cows to be exposed to unfamiliar bulls 30–32 d later did not (P > 0.10) alter: (1) the proportion of cows that resumed cycling activity; and (2) postpartum interval to resumption of ovarian cycling activity compared to cows exposed to familiar bulls. However, 32% more (P < 0.05) cows exposed to bulls (BEF and BEU) resumed cycling activity by approximately 14.8 d before cows that were exposed to OVX cows (CEF and CEU). We conclude that the familiarity of first-calf cows to either bulls or ovariectomized cows, did not affect the postpartum occurrence of cycling activity or the interval from calving to resumption of ovulatory cycles. However, bull exposure, whether familiar or unfamiliar, stimulates first-calf cows to resume ovulatory cycles sooner after calving than if they are not exposed to bulls.     

A brief report on intra-species aggressive biting in a goat herd

This study aimed at analysing the effects of age, horn and places on biting and butting as intra-species aggressive activities. Seventy-two Turkish Saanen goats were used as animal material and 22,686 aggressive behaviours were recorded in different places from a total of 118 h direct observation. Of the observations of aggressive behaviours, 32.7% was biting behaviour and the rest was butting behaviour. The frequency of biting behaviour in 3 or more years old goats was significantly higher than that of biting behaviour in 1 and 2 years old animals (P ≤ 0.01). The observations revealed that horned or hornless goats exhibited biting behaviour; however the frequency of biting behaviour in hornless goats was 2.38 times higher than in horned goats (P ≤ 0.01). Biting and butting behaviours were found to be well correlated with the area of places (P ≤ 0.01). As the area of places got narrowed, the frequency of biting increased. However, such a trend was not observed in butting behaviour. The frequency of butting behaviour again increased with the increase in social hierarchy (P ≤ 0.01), whereas the frequency of biting behaviour was not affected by social hierarchy (P = 0.30). In conclusion, intra-species biting behaviour, which is thought to have developed as a result of horn absence, should be questioned whether this is unique to the herd or to the genotype.     

Effects of nutrient restriction on the metabolic profile of Bos indicus-influenced and B. taurus suckled beef cows

Recent research from our group demonstrated that Bos indicus-influenced suckled beef cows had greater resilience to withstand nutrient restriction and establish pregnancy compared with B. taurus cows exposed to the same conditions. To further understand these findings, differences in metabolic profile between these same B. indicus-influenced and B. taurus females were explored. Suckled beef cows (n = 134) were enrolled in a completely randomized design with a 2 × 2 factorial arrangement of treatments. On day − 21, Angus (AN; Bos taurus) and Brangus (BN; B. indicus-influenced) cows were randomly assigned to 1) a diet that met daily energy maintenance requirements (MAINT), or 2) a diet that restricted intake to 70% of the daily energy maintenance requirements (RESTR). Cows were exposed to an estrus synchronization protocol and received an embryo 7 d after ovulation was pharmacologically induced on day 0. Blood samples were collected on days − 21 and 19 to determine circulating concentrations of non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), insulin, glucose, and IGF-1. Pregnancy status after embryo transfer was determined on day 28. As a consequence of the proposed diets, cows in the RESTR diet had less body condition score (BCS) on day 19 (P = 0.008) across breed types. Moreover, BCS change from day − 21 to 19 was included as independent covariate into subsequent analyses, allowing for the comparison of breed types under an equivalent level of body reserve mobilization. A breed × diet interaction was observed for plasma insulin (P = 0.03) and IGF-1 (P = 0.04) on day 19, where AN–RESTR cows had less plasma concentrations on day 19 compared with AN–MAINT cows. Diets did not impact (P > 0.10) plasma insulin and IGF-1 concentrations in BN cows. No diet or breed effects were observed in circulating concentrations of NEFA, BHB, and glucose (P > 0.10). Across breed types and nutritional treatment, there was positive linear effect (P ≤ 0.04) of plasma concentrations of insulin and IGF-1 on the probability of pregnancy to fixed-time embryo transfer. In summary, the negative impacts of nutrient restriction on the somatotropic axis, independently of body tissue mobilization, were heightened in Bos taurus females compared with B. indicus-influenced cohorts, which corroborate with the differences observed in fertility between these subspecies.     

Designing better water troughs: 2. Surface area and height,but not depth,influence dairy cows’ preference

Water consumption affects milk production of dairy cows. In a previous study, we found that dairy cows preferred to drink from larger than from smaller troughs and that intake was higher when water was offered in the larger, preferred troughs. In this study, we investigated some of the trough's characteristics that may underlie such preference. The volume of water consumed, time spent drinking and number of sips taken by cows (n = 18) were compared when water was offered in two troughs differing in surface area (1.13 m² or 0.28 m²; experiment 1), height (30 cm or 60 cm; experiment 2) or depth (30 cm or 60 cm; experiment 3). In each experiment, each cow was tested individually for six consecutive days with the troughs randomly placed in each side. In experiment 1, cows took more sips (P < 0.01), spent more time drinking (P < 0.01) and drank more water (P < 0.01) from the trough with larger surface area. In experiment 2, cows took more sips from the higher than from the lower trough (P < 0.02) and showed a tendency to consume more water (P = 0.08) and to spend more time drinking (P = 0.08) from the higher than from the lower trough. Trough depth did not influence any of the variables recorded.     

Cotyledonary responses to maternal selenium and dietary restriction may influence alterations in fetal weight and fetal liver glycogen in sheep

To examine the effects of maternal supranutritional selenium (Se) and nutrient restriction during mid and late gestation on placental characteristics and fetal liver glycogen, ewes received either adequate Se (ASe) or high Se (HSe) prior to breeding. On d 64 of gestation, ASe and HSe ewes remained at 100% of requirements (controls; CON) or were restricted (RES; 60% of requirements). On d 135 of gestation, fetal weight (P ≤ 0.08) was greatest in both HSe and CON ewes. Placentome number, mass, and caruncular and cotyledonary weight were not different (P ≥ 0.17) among treatments. Fetal mass:placental mass ratio was less (P = 0.06) in RES compared to CON ewes. Compared to ASe, HSe exhibited increased (P ≤ 0.08) cellular proliferation and DNA concentration and decreased (P = 0.07) cellular size in cotyledonary tissue. Nutritional restriction decreased (P ≤ 0.08) cotyledonary protein concentration and cellular size. VEGF receptor 1 (Flt) mRNA in cotyledonary tissue was greater in HSe compared with ASe ewes (P = 0.06) and in RES compared with CON ewes (P = 0.08). There was no effect of diet on caruncular growth variables (P ≥ 0.13) or on placental vascularity (P ≥ 0.11). Progesterone was greater (P ≤ 0.08) in ASe–RES ewes compared to all groups at d 90 and ASe–CON and HSe–CON at d 104. Although fetal glucose and cortisol concentrations were not affected by diet, fetal liver glycogen was greater (P = 0.04) in ASe–RES compared to ASe–CON and HSe–RES ewes with HSe–CON being intermediate. Both Se and nutritional plane may impact placental function and fetal growth, as fetal weight and liver glycogen are altered despite similar placental vascularity measurements.     

Protective effect of combined therapy with dithiothreitol,zinc and selenium protects acute mercury induced oxidative injury in rats

The present study was undertaken to establish mode of action, comparative therapeutic efficacy and safety evaluation of dithiothreitol (DTT) supplemented with Zn and Se against dimethylmercury in rats. Adult male albino rats of Sprague-Dawley strain (150 ± 10 g, n = 6 per group) were exposed a bolus dose of dimethylmercury (10 mg/kg, p.o.) for once only followed by DTT (15.4 mg/kg, i.p.) along with the combination of antioxidants Zn and Se (2 mmol/kg and 0.5 mg/kg, p.o.) after 72 h of toxicant administration for three days. The results showed a significant (P ≤ 0.05) increase in the activities of AST, ALT, alkaline phosphatase, lactate dehydrogenase, in serum after toxicant administration. This was accompanied by histopathological observations. A significant rise was observed in lipid peroxidation level and mercury ion concentration however reduced glutathione content decreased in liver, kidney and brain. A significant (P ≤ 0.05) decrease in the activity of acetyl cholinesterase was also seen in different regions of brain. Combined treatment of DTT along with Zn and Se significantly (P ≤ 0.05) recouped the alterations in the enzymatic activities of serum and reversed the tissue biochemical and histopathological changes of liver, kidney and brain. Our results demonstrate that combined treatment of thiol chelator (DTT) along with antioxidants (Zn and Se) plays an important role against dimethylmercury induced tissue damage and hepatic, nephro and neurotoxicity.     

Dairy cows' fear of people: social learning, milk yield and behaviour at milking

We examined the effects of the presence of an unfamiliar, a gentle or an aversive handler during milking on behaviour and milk yield, and whether cows can learn to approach or avoid a handler by observing the neighbouring cow's responses. In Experiment 1, Danish Friesian cows (n=16) were treated gently (offering hay and concentrates) by one handler and aversively (hit every 15s on the head with the hand) by another handler for six periods of 2min each. The two handlers wore different coloured overalls, and each cow received either gentle or aversive treatment in the first week and the other treatment the following week. All cows kept a longer distance to the aversive than to the gentle handler in a 1min test after treatment. Milk yield and residual milk did not differ when the aversive or the gentle handler was standing in front of the cow during milking, although the cows moved their legs and tail less when the aversive handler was present. When an unfamiliar person was standing in front of the cows during milking, behaviour and milk yield did not differ from control milkings. Cows and heifers (n=10) that had observed their neighbours receiving gentle treatment by one handler and aversive treatment from another handler did not differ in the distance they kept from these two handlers. In Experiment 2, cows (n=15) that had observed the neighbours receiving a gentle treatment (eight times for 2min) kept a shorter distance to that handler after treatment of their neighbours, and the distance they kept was correlated with the distance kept by the neighbouring cows. This suggests that responses of observer cows may be affected by the responses of the cows being treated. The cows rapidly learned to avoid an aversive handler, but although the cows showed clear avoidance response to the aversive handler there was no effect on milk yield when the aversive handler was present at milking.     

Brain fixation for analysis of brain lipid-mediators of signal transduction and brain eicosanoids requires head-focused microwave irradiation: An historical perspective

Endothelin-1 (ET-1) has been reported to mediate prostaglandin (PG) F₂α (PGF₂α)-induced luteolysis. Prostaglandins E (PGE; PGE₁ + PGE₂) are associated with implantation, maternal recognition of pregnancy, and are antiluteolytic and luteotropic in vitro and in vivo. ET-1 increased PGE secretion by bovine luteal tissue in vitro from cows where estrus was not synchronized or when estrus was synchronized with lutalyse and did not affect luteal PGF₂α or progesterone secretion, which does not support the concept that ET-1 is luteolytic or mediates PGF₂α luteolysis. Therefore, the objective of this experiment was to determine whether ET-1 infused every 6 h from 2400 h on day 10–1800 h on day 18 of the ovine estrous cycle either into the interstitial tissue of the ovarian vascular pedicle (IP) or intrauterine (IU) adjacent to the luteal-containing ovary was luteolytic in ewes. Treatments were: Vehicle-IP; Vehicle-IU; ET-1-IP; or ET-1-IU. Weights of corpora lutea differed (P ≤ 0.05) among treatment groups. Weights of corpora lutea at 1800 h on day 18 were: VEH-IP—247 ± 38 mg; VEH-IU—195 ± 31 mg; ET-1-IP—626 ± 74 mg; and ET-1-IU—542 ± 69 mg. Luteal weights on day 18 in ET-1-IP or ET-1-IU-treated ewes did not differ (P ≥ 0.05), but were heavier (P ≤ 0.05) than in the Vehicle-IP or Vehicle-IU treatment groups which did not differ (P ≥ 0.05). Profiles of progesterone in jugular venous plasma of both control groups treated with Vehicle-IP or Vehicle-IU were lower (P ≤ 0.05) than in ewes treated with ET-1-IP or ET-1-IU, which did not differ (P ≥ 0.05) between ET-1-IP or ET-1-IU treatment groups. Treatment with ET-1-IP or ET-1-IU increased (P ≤ 0.05) the PGE:PGF₂α ratio when compared to the Vehicle-IP or Vehicle-IU treatment groups, which did not differ (P ≥ 0.05) between each other. In summary, ET-1 prevented the decrease in luteal weights and the decline in progesterone, but increased the PGE:PGF₂α ratio when compared to controls. Therefore, it is concluded that ET-1 is not luteolytic in ewes, but instead may be luteotropic or antiluteolytic by altering uterine secretion of the PGE:PGF₂α ratio, since PGE₁ or PGE₂ are luteotropic in vitro and in vivo, PGE₁ or PGE₂ prevent PGF₂α-induced luteolysis in vitro and in vivo, and PGE₁ and PGE₂ increase two-fold in ewe endometrium to prevent luteolysis during early pregnancy.     

Effect of short and long periods of separation on agonistic behaviour,injuries and stress in Hérens cows kept in loose housing

Hérens cows are typically not dehorned and are therefore housed in tie-barns during winter. Recently, however, farmers have started to also use loose housing systems. They separate single cows from their herd for periods of a few days to ensure undisturbed calving and to avoid excessive activity caused by animals in oestrus. As these cows are highly motivated to fight, the re-introduction of individuals after separation is usually associated with increased agonistic behaviour. The aim of this study was to compare the effects of the length of separation with regard to behaviour, injuries and stress response.The study was conducted with 45 focal horned Hérens cows kept in four groups of 10, 20, 18 and 21 cows respectively on two Swiss farms: two groups were kept as suckler cows and two groups as dairy cows. Each focal cow was separated on two occasions, once for a short (median: 1 day; high oestrus in dairy, late pregnancy or lactation in suckler cows) and once for a longer (median: 2 days; high oestrus in dairy, calving in suckler cows) period. During the 6 h following the re-introduction, agonistic behaviour was recorded. Occurrence of fresh wounds was noted 10 h after re-introduction. As an indicator of physiological stress, faecal samples were collected and concentrations of the cortisol metabolite 11,17-dioxoandrostanes (11,17-DOA) were determined. All data were analysed using generalised linear mixed-effects models.Frequency and duration of agonistic interaction increased with longer separation (p < 0.02) and quickly decreased during the hours following the re-introduction of the focal cow (p < 0.001). The risk of injuries did not significantly change with duration of separation. Separating the cow from her group brought about an increase in concentration of 11,17-DOA (p = 0.012) that decreased over time (p < 0.001). Interestingly, concentrations during the re-introduction phase were lower in comparison with the separation phase (p < 0.001). The concentration of 11,17-DOA was lower during the longer separations (p = 0.018). We did not find any difference of practical importance in how cows reacted to long compared to the short separation related to the different hormonal states of dairy and suckler cows during separation, nor related to the changes in hormonal state within the suckler cows.In conclusion, the duration of a separation of a single Hérens cow from her herd should be minimised so as to reduce negative effects resulting from agonistic interactions.     

Heifer nutrition during early- and mid-pregnancy alters fetal growth trajectory and birth weight

Maternal nutrient intake during gestation can alter fetal growth. Whilst this has been studied extensively in the sheep, less is known about effects in the bovine. Composite-breed beef heifers were allocated to either a high (H/? = 76 MJ metabolisable energy (ME) and 1.4 kg crude protein (CP)) or low (L/? = 62 MJ ME and 0.4 kg CP daily) nutritional treatment at artificial insemination. Half of each nutritional group changed to an opposite nutritional group at the end of the first trimester (?/H = 82 MJ ME and 1.4 kg CP; ?/L = 62 MJ ME and 0.4 kg CP daily), resulting in 4 treatment groups: HH (n = 16); HL (n = 19); LH (n = 17); LL (n = 19). During the third trimester all heifers were fed the same diets. Fetuses were measured at 4-weekly intervals beginning at day 39 of gestation. Calves were also measured at birth for physical body variables. Low maternal nutrient intake was associated with decreased crown-rump length at day 39 (P < 0.01) and increased thoracic diameter at day 95 (P < 0.01). Umbilical cord diameter was reduced in L/? fetuses in the first trimester (P < 0.05) but was greater in ?/L fetuses in the second trimester compared to their respective H counterparts (P < 0.05). Calf birth weight was decreased in association with ?/L maternal diets (P < 0.05). In conclusion, fetal development of cattle may be affected by maternal nutrition as early as day 39 of gestation. This may be followed by either compensatory fetal growth, or alternatively, preferential fetal tissue growth that is dependant upon maternal nutrition. Clearly, calf birth weight may be altered by maternal nutrition during mid-gestation.     

The effects of blindfolding on behavior and heart rate in beef cattle during restraint

Use of a blindfold or hood during handling and restraint has been suggested for many wild and captive animals. Two experiments were conducted to determine the effects of blindfolds on beef cattle during restraint. In Experiment 1, 60 beef heifers, naı̈ve to the restraint facility, were randomly assigned to either visual restriction (blindfold) or no visual restriction (control) and tested daily during a 4-day trial to determine the effects during restraint. Heart rate (HR) was measured via telemetry, during a baseline period prior to treatment and continuously recorded during a 1-min period of restraint, which included some manipulation of the animal. Manipulation was initiated 15 s into the restraint period. Two persons simultaneously approached the animal one on either side, grasped the ears, and touched the neck, sides and rump to simulate normal management tasks. Electronic strain gauges attached to the head gate quantified the animal’s struggle during this procedure. These were used to determine the average and maximum exertion forces upon the head gate during restraint. The association between treatment, sample time (day 0–4), animal weight and the various outcome measures were analyzed using a generalized estimating equation method. Mean HR of heifers did not differ at the end of the treatment (95.04±4.66 bpm ) (P=0.64), but the HR tended to decrease more for blindfolded heifers compared to controls during restraint (average decrease 16.3±3.2 bpm and 14±2.9 bpm, respectively) (P=0.10). The average exertion forces applied by blindfolded heifers against the head gate were 23% lower (P<0.05) during the 1-min period and maximum forces were 28% lower (P<0.01). Heart rate and exertion forces declined over the 4 days for both treatment groups (P<0.001). In Experiment 2, 93 commercial beef calves (average age 92.9±2.0 days) were randomly assigned to either visual restriction (blindfold) (n=46) or no visual restriction (control) (n=47) treatments. Behavioral responses to treatment were quantified by measuring the amount of movement and recording the number of vocalizations while the calves were restrained for 1 min on a calf tilt table. Movement was recorded by an electronic device attached to a weighing platform that held the tilt table. After 30 s of restraint, one experimenter touched the animal’s ear while the other touched the neck, to simulate ear tagging and vaccination. Blindfolded calves moved 44% less than the control group (P<0.01). However, the number of vocalizations that occurred during the 1-min test period did not differ (P>0.05) between treatments. Overall, blindfolding cattle reduced the amount of struggle and tended to lower heart rate. Therefore, blindfolding may be advantageous during the routine invasive procedures commonly performed on cattle.     

Prostaglandin E1 (PGE1), but not prostaglandin E2 (PGE2), alters luteal and endometrial luteinizing hormone (LH) occupied and unoccupied LH receptors and mRNA for LH receptors in ovine luteal tissue to prevent luteolysis

Loss of luteal progesterone secretion at the end of the ovine estrous cycle is via uterine PGF₂α secretion. However, uterine PGF₂α secretion is not decreased during early pregnancy in ewes. Instead, the embryo imparts a resistance to PGF₂α. Prostaglandins E (PGE; PGE₁ + PGE₂) are increased in endometrium and uterine venous blood during early pregnancy in ewes to prevent luteolysis. Chronic intrauterine infusion of PGE₁ or PGE₂ prevents spontaneous or IUD, estradiol-17β, or PGF₂α-induced premature luteolysis in nonbred ewes. The objective was to determine whether chronic intrauterine infusion of PGE₁ or PGE₂ affected mRNA for LH receptors, occupied and unoccupied receptors for LH in luteal and caruncular endometrium, and luteal function. Ewes received Vehicle, PGE₁, or PGE₂ every 4 h from days 10 to 16 of the estrous cycle via a cathether installed in the uterine lumen ipsilateral to the luteal-containing ovary.Jugular venous blood was collected daily for analysis of progesterone and uterine venous blood was collected on day-16 for analysis of PGF₂α and PGE. Corpora lutea and caruncular endometrium were collected from day-10 preluteolytic control ewes and day-16 ewes treated with Vehicle, PGE₁ or PGE₂ for analysis of the mRNA for LH receptors and occupied and unoccupied receptors for LH. Luteal weights on day-16 in ewes treated with PGE₁ or PGE₂ and day-10 control ewes were similar (P ≥ 0.05), but were greater (P ≤ 0.05) than in day-16 Vehicle-treated ewes. Progesterone profiles on days 10–16 differed (P ≤ 0.05) among treatment groups: PGE₁ > PGE₂ > Vehicle-treated ewes. Concentrations of PGF₂α and PGE in uterine venous plasma on day-16 were similar (P ≥ 0.05) in the three treatment groups. Luteal mRNA for LH receptors and unoccupied and occupied LH receptors were similar (P ≥ 0.05) in day-10 control ewes and day-16 ewes treated with PGE₂ and were lower (P ≤ 0.05) in day-16 Vehicle-treated ewes. PGE₂ prevented loss (P ≤ 0.05) of day-16 luteal mRNA for LH receptors and occupied and unoccupied LH receptors. Luteal and caruncular tissue mRNA for LH receptors and occupied and unoccupied LH receptors were greater (P ≤ 0.05) on day-16 of PGE₁-treated ewes than any treatment group. mRNA for LH receptors and occupied and unoccupied receptors for LH in caruncules were greater (P ≤ 0.05) in day-16 Vehicle or PGE₂-treated ewes than in day-10 control ewes. It is concluded that PGE₁ and PGE₂ share some common mechanisms to prevent luteolysis; however, only PGE₁ increased luteal and endometrial mRNA for LH receptors and occupied and unoccupied LH receptors. PGE₂ prevents a decrease in luteal mRNA for LH receptors and occupied and unoccupied receptors for LH without altering endometrial mRNA for LH receptors or occupied and unoccupied receptors for LH.     

The effect of ice-slushy consumption on plasma vasoactive intestinal peptide during prolonged exercise in the heat

The aim of this study was to determine the effect of exercise in the heat on thermoregulatory responses and plasma vasoactive intestinal peptide concentration (VIP) and whether it is modulated by ice-slushy consumption. Ten male participants cycled at 62% $\dot{V}{\mathrm{O}}_2$max for 90 min in 32 °C and 40% relative humidity. A thermoneutral (37 °C) or ice-slushy (−1 °C) sports drink was given at 3.5 ml kg⁻¹ body mass every 15 min during exercise. VIP and rectal temperature increased during exercise (mean±standard deviation: 4.6±4.4 pmol L⁻¹, P=0.005; and 1.3±0.4 °C, P<0.001 respectively) and were moderately associated (r=0.35, P=0.008). While rectal temperature and VIP were not different between trials, ice-slushy significantly reduced heat storage (P=0.010) and skin temperature (time×trial interaction P=0.038). It appears that VIP does not provide the signal linking cold beverage ingestion and lower skin temperature in the heat.