Steer stress levels during long distance transport throughout the year in Japan

The objective of this study was to investigate transportation conditions and behavioral and physiological responses of beef steers to long distance commercial transport throughout the year Japan. Japanese Black × Holstein steers (7.9 ± 0.6 months of age; 320.0 ± 19.0 kg) were transported by truck in spring (n = 8), summer (n = 5), autumn (n = 8) and winter (n = 5). Transport distances (time) were 1020.6 km (25 h including lairage periods): 615.4 km (6.4 h) on expressways, 163.2 km (3.7 h) on arterial roads and 242.0 km (10.5 h) by ferry. The space allowance of the truck was about 1.6 m²/head in all seasons. Internal temperatures of the truck were 14.7 ± 4.7°C in spring, 27.9 ± 2.6°C in summer, 24.4 ± 2.8°C in autumn and 9.2 ± 4.3°C in winter. Although internal noise and airflow velocity of the truck were louder and greater while moving on expressways (101.1 ± 8.3 dB and 1.50 ± 1.50 m/s) than on arterial roads (92.0 ± 15.2 dB and 1.32 ± 1.41 m/s) (both P < 0.05), more steers lay down while moving on expressways (P < 0.001). Blood glucose, plasma cortisol, and serum triiodothyronine (T3) concentrations and ALT activity were higher in spring (all P < 0.05). This could be explained by that vibration acceleration (m/s²) of the truck in the longitudinal direction was greater in spring (?0.19 ± 0.43) than in the other seasons (?0.14 ± 0.09 in summer, ?0.15 ± 0.20 in autumn and ?0.15 ± 0.13 in winter) (all P < 0.05). Heart rate, serum concentrations of T₃, total cholesterol, total protein, and AST and ALT activities were higher just after transport than 1 week after transport (all P < 0.05). However, transport stress should be not severe, since no difference between before and after transport was shown on concentrations of plasma cortisol, blood lactate and serum NEFA, serum triglyceride and serum pH and liveweight.     

Choice of attractive conditions by beef cattle in a Y-maze just after release from restraint: Effect of sheep

To provide useful information on how to moderate post‐handling stress, Angus heifers (n = 157) were individually allowed to enter a choice area after 2 min of restraint in a crush and to choose between two pens. After the animal had chosen a pen, free access was given to both test pens and the choice area for a further 5 min. The behaviors during choice and after the first choosing were observed. In experiment 1, each heifer was given one of the following choices: pen with three familiar heifers (peers) versus pen with six sheep (sheep; n = 30); peers versus the bare pen (bare; n = 30); sheep versus bare (n = 30). When the choice combination was peers versus bare, more heifers than expected by chance chose the peers pen (χ² = 4.80; P < 0.05). However, when one of the other choice combinations was given, there was no significant difference between the number choosing a pen and the expected value. After the first choice, more heifers entered the peers pen than the bare pen (P < 0.05) or the sheep pen (P < 0.10). In experiment 2, another 67 heifers were given one of the following choices: peers versus pen with a novel object (NO; n = 19); sheep versus NO (n = 22); bare versus NO (n = 26). There was no significant difference between the number of heifers choosing a pen and the expected value in any choice combination. However, more heifers entered the peers pen than the NO pen (P < 0.01). It is concluded that sheep were not as attractive as peers, but sheep were not fearful animals for cattle.     

Intramuscular Selenium Administration in Selenium-Deficient Cattle

Nine recently weaned Hereford heifers were randomly assigned to a control group (n = 3) or a treatment group (n = 6). The animals were selenium (Se) deficient (mean ± SD blood Se concentration = 0.024 ± 0.012 μg/mL). They were maintained on a selenium-deficient diet, and on day 0 of the study the treatment group was given 0.05 mg Se/kg body weight intramuscularly, while the control group received a placebo. The Se concentration of blood, serum, and urine as well as the glutathione peroxidase (GSH-Px) activity of blood and serum was measured over an 84-day period. Peak blood Se and serum Se concentrations (mean ± SD) in the treatment group occurred at 5 hours postinjection and were 0.131 ± 0.028 μg/mL and 0.154 ± 0.027 μg/mL, respectively. The mean blood Se concentration of the treatment group was greater (P < .05) than that of the control group for the first 28 days after injection. The mean serum Se concentration of the treatment group was greater (P < .05) than that of the control group for all times after injection, except for day 56. The mean (±SD) blood GSH-Px activity of the treatment group (12.0 ± 2.3 mU/min/mg hemoglobin) was increased (P < .05) over the control group (2.0 ± 1.4 mU/min/ mg hemoglobin) by day 28 and continued to be greater (P < .05) throughout the 84 day postinjection period. The blood GSH-Px activity and the blood Se concentrations in the treatment group heifers did not reach concentrations considered indicative of Se adequacy (30 mU/min/mg hemoglobin and 0.10 μg/mL, respectively) except briefly, at 5 hours postinjection when the blood Se concentration of the treatment group was 0.131 ± 0.028 μg/mL. The mean serum GSH-Px activity of the treatment group did not differ at any time from that of the control group (P≥ .17). The mean (±SD) fractional excretion (FE) of Se, as an estimate of Se excretion, was greater (P < .05) in the treatment group heifers (n = 5; 6.2 ± 2.5%) than in the control heifers (n = 3; 1.3 ± 0.6%) at 24 hours postinjection. The mean (±SD) weight gain, from day 0 to day 84, for the treatment group heifers was 63.0 ± 18.1 kg and the mean weight gain for the control group heifers was 53.1 ± 7.3 kg at 84 days postinjection and there was no difference between the groups (P < .39). Conclusions drawn from this study include: 1) the increase in blood GSH-Px activity occurs approximately 28 days after Se injection given to Se-deficient heifers, 2) a single label dose of injectable Se does not result in blood Se concentrations or blood GSH-Px activity normally considered to be adequate, 3) the label dose of injectable Se, although therapeutically beneficial for nutritional myodegeneration (NMD), does not seem to be a desired method for long-term Se supplementation of cattle consuming a Se-deficient diet, and 4) blood Se is a better predictor of Se status than serum Se. (Journal of Veterinary Internal Medicine 1993; 7:342–348. Copyright © 1993 by the American College of Veterinary Internal Medicine.)     

Oestrus detection techniques and insemination strategies in Bos indicus heifers synchronised with norgestomet-oestradiol

SUMMARY Oestrus was synchronised in 57 Bos indicus heifers using norgestometoestradiol and pregnant mare serum gonadotrophin. Oestrus was detected by observations made at six-hourly intervals, using oestrogen-treated and chin-ball harnessed steers, heatmount detectors, tail-paint and visual observation. Heifers were inseminated once at either a fixed time of 49.2 ± 0.4 h (mean ± SE; n = 29) after implant removal or 12.6 ± 1.5 h (n = 28) after oestrus was detected. The mean (± SE) time to the onset of oestrus was 47.1 ± 1.9 h, while 90% of heifers recorded in oestrus were detected within 66 h of implant removal. Heatmount detectors were significantly more efficient at detecting oestrus than chin-ball harnessed steers, tail paint or visual observation (P < 0.001). A higher pregnancy rate was obtained in heifers inseminated after oestrus detection compared with heifers inseminated at a fixed-time (57.1 vs 34.5%; P = 0.043) and a higher pregnancy rate was obtained in heifers classified as easy to inseminate compared with heifers classified as difficult to inseminate (57.8 vs 0%, P < 0.001). We conclude that heatmount detectors are an efficient means of detecting oestrus in synchronised B indicus heifers and that pregnancy rates can be increased when insemination follows oestrus detection compared with a fixed-time insemination regimen.     

Artificial insemination of Bos indicus heifers: The effects of body weight, condition score, ovarian cyclic status and insemination regimen on pregnancy rate

SUMMARY Effects of body weight, condition score, ovarian cyclic status and insemination regimen on pregnancy rates were investigated in 164 Bos indicus heifers synchronised with norgestomet-oestradiol and pregnant mare serum gonadotrophin (PMSG). Oestrus detection techniques were also compared. Heifers were inseminated at either a fixed time (group 1, n = 83) of 48.0 ± 0.2 h (mean ± SEM) after implant removal or at 8.9 ± 0.5 h after oestrus was detected (group 2, n = 81). Group 2 heifers that were not detected in oestrus by 72 h after implant removal were inseminated at that time. Oestrus was detected for the purpose of insemination using heatmount detectors. Tail-paint and oestrogen treated, chin-ball harnessed steers were used to compare the efficiency of oestrus detection. The probability of ovarian cyclicity increased with increasing body weight and condition score (P < 0.001). A higher proportion of heifers that were acyclic at the commencement of treatment, compared with cyclic heifers, were detected in oestrus at the time of insemination in the fixed-time inseminated group (P <0.01). Analysis of covariance revealed that intervals from implant removal to oestrus were influenced by ovarian cyclic status (P < 0.01) and insemination group (P < 0.05). A higher pregnancy rate (%± SEM) was obtained in acyclic compared with cyclic heifers in the group 1 heifers (50.0 ± 10 vs 28.1 ± 6; P = 0.055) but not among the group 2 heifers (45.8 ± 10 vs 49.1 ± 7; P = 0.787). The probability of pregnancy was found to be associated negatively with body weight (P = 0.01) while a higher pregnancy rate was obtained in the group 2 compared with group 1 heifers (48.2%vs 34.9%; P = 0.093). The efficiency of oestrus detection was highest using heatmount detectors compared with tail-paint and chin-ball harnessed steers (90.7%vs 37.0% and 23.5%, respectively; P < 0.0001). We conclude that pregnancy rates can be increased in extensive environments when insemination follows oestrus detection using heatmount detectors compared with a fixed-time insemination. The fertility of heifers inseminated at a fixed time is influenced by ovarian cyclic status due to its influence on oestrus-to-insemination intervals.     

Seasonal diet composition and forage selectivity of Boer goats in a semi-arid gypsophilous grassland

Botanical and chemical compositions of Boer goat diets, determined with repeated collection of forage samples taken from the goat’s mouth, were studied in a gypsophilous grassland during four seasons of the year. Ten pluriparous goats were used to collect selected forage species. Shrubs were a minor dietary component throughout the year (<7.5%). Goats selected more (p?<?0.01) grass during autumn and winter (34.2–37.8%) than during spring (21.2%) and summer (29.0%). During all seasons goat diets were dominated by forbs (>59%). Diets were lowest (p?<?0.05) in percentage of crude protein during spring, summer and autumn (13.2?±?3.5, 13.2?±?2.4 and 14.2?±?3.9, respectively) than winter (17.5?±?2.9) with levels above the recommended quantities for goats throughout the year. In vitro dry matter digestibility of forages selected by goats did not differ between seasons (range 47.4–53.3%). It was concluded that in this particular ecosystem goats preferred forb species over grasses across all seasons. In addition, goats maintained relatively stable diet quality by forage-class mixing of diets.     

Relation of reproductive performances and rectal palpation for luteum function of heifers 7 days after estrus

Diagnosis of corpus luteum (CL) function by rectal palpation (RP) has been widely used for recipient selection of embryo transfer (ET), a technology essential for genetic improvements in cattle. To examine the accuracy of RP diagnosis method, the relationship between RP‐based CL function and reproductive performance was compared in this study. In Experiment 1, CL of Holstein heifers on day 7 after estrus was classified into functional or hypoplastic by RP, and the results were compared with ultrasonographic (US) images and plasma progesterone (P4) levels. As a result, heifers with functional CL judged by RP had a mean maximum CL diameter of 20.1 ± 3.1 mm on US and a mean P4 concentration of 8.1 ± 2.3 ng/mL. These values were significantly greater than those of heifers with hypoplastic CL (12.4 ± 5.4 mm, 4.0 ± 2.8 ng/mL) (P < 0.001). In Experiment 2, the length of the estrus cycle was examined between functional CL and hypoplastic CL. The rate of heifers with a normal estrus cycle length with 18–25 days was significantly lower with hypoplastic CL than with functional CL (16/24 vs. 43/46, P < 0.01). In Experiment 3, 543 inseminated heifers were similarly classified by CL function by RP 7 days after estrus. The heifers with functional CL showed higher pregnancy rate compared with the heifers with hypoplastic CL (75.2 vs. 47.9%, P < 0.0001). Finally, the CL function of 66 heifers was examined by RP on day 7 post‐estrus, and ET was performed in 49 (74.2%) heifers with functional CL. As a result, 27 (55.1%) of them became pregnant. Taken together, these results reconfirm that RP on day 7 after estrus is useful for selection of heifers with functional CL.     

Effects of month of breeding on reproductive efficiency of Holstein cows and heifers inseminated with sex-sorted or conventional semen in a hot environment

The main objective of this study was to assess the effect of month of breeding on reproduction performance of Holstein heifers and cows inseminated with sex-sorted or conventional semen in a hot environment. Pregnancy per artificial insemination (P/AI; 64,666 services over an 8-year period) both in heifers (n?=?22,313) and cows (n?=?42,353) from a large dairy herd in northern Mexico (26°N) were evaluated with the GENMOD procedure of SAS, with respect to month of AI. Overall, P/AI with sex-sorted semen was greater (P?<?0.01) in heifers (41.6 %) than cows (17.3 %). P/AI for cows serviced with conventional semen was 10 % points higher (P?<?0.01) in January and December (31 vs. 21 %) than cows serviced with sex-sorted semen. While there was no difference in P/AI between the sex-sorted sperm and conventional semen in cows inseminated in July (16 and 18 %, respectively), P/AI plummeted for both groups of cows during the summer and fall (more severe heat stress). P/AI was not different between heifers serviced with sex-sorted or conventional semen during the hottest months of the year (July to October). However, during the coldest month of the year (January and February), P/AI was 10 percentage points greater (P?<?0.01) in heifers serviced with conventional than sex-sorted semen. It was concluded that in this hot climate cow and heifer fertility declined in the summer and fall when inseminated with conventional semen. However, the use of sex-sorted semen during summer and fall did not compromise the breeding success in heifers. Thus, this data suggest that sex-sorted semen promotes some embryonic thermoprotective mechanism, which leads to a marginal summer and fall fertility depression with this type of semen in this particular hot environment.     

Pregnancy‐Induced ISG‐15 and MX‐1 Gene Expression is Detected in the Liver of Holstein–Friesian Heifers During Late Peri‐Implantation Period

The bovine embryonic signal interferon‐τ (IFN‐τ) produced by the trophoblast is known to pass through the uterine fluid towards the endometrium and further into the maternal blood, where IFN‐τ induces specific expression of interferon‐stimulated gene expression (ISG), for example in peripheral leucocytes. In sheep, it was shown experimentally by administration of IFN‐τ that ISG is also detectable in the liver. The objective was to test whether ISG can be detected in liver biopsy specimens from Holstein–Friesian heifers during early pregnancy. Liver biopsies were taken on day 18 from pregnant and non‐pregnant heifers (n = 19), and the interferon‐stimulated protein 15 kDa (ISG‐15) and myxovirus‐resistance protein‐1 (MX‐1) gene expression was detected. The expression of both MX‐1 (p: 24.33 ± 7.40 vs np: 9.00 ± 4.02) and ISG‐15 (p: 43.73 ± 23.22 vs 7.83 ± 3.63) was higher in pregnant compared to non‐pregnant heifers (p < 0.05). In conclusion, pregnancy induced ISG‐15 and MX‐1 gene expression in the liver already at day 18 in cattle.     

Effect of protein supplementation on reproductive and productive performance in <Emphasis Type="Italic">Bos indicus</Emphasis> × <Emphasis Type="Italic">Bos taurus</Emphasis> heifers raised in the humid tropics of Costa Rica

In order to evaluate the effect of protein supplementation on the productive and reproductive performance of heifers, 45 Bos indicus × Bos taurus heifers, 673 ± 146 days of age and weighing about 340 kg, were divided into two groups. The control group (n = 23) continued without supplementation, but the supplemented group (SG; n = 22) received concentrate at a rate of 1% BW kg per day. Animals were adapted to the concentrate over a 15-day period and then supplemented for 30 days, after which estrus was synchronized using a progesterone implant. Back fat thickness (BFT) was assessed by ultrasound. The SG had better average daily weight gain than the nonsupplemented group (0.63 ± 0.16 vs. 0.51 ± 0.13 kg/day, P < 0.05) and tended to show a better percentage ovulation (P < 0.10, 77% vs. 57%, respectively). However, this tendency was not reflected in the final pregnancy rates. No differences were observed between groups in dry matter intake and body condition scores. SG with a high BFT (>0.70 cm) showed a better ovulation percentage than those with low BFT (<0.69 cm; P < 0.01). Additionally, the pregnancy rate of supplemented heifers with high BFT tended to be better than heifers with low BFT in this same group (67% vs. 30%, respectively, P < 0.10). It is concluded that protein supplementation improved reproductive performance and that ultrasonography to measure BFT may be used to estimate reproductive performance.     

Carcass characteristics of Hanwoo (Korean cattle) from different sex conditions, raising altitudes and slaughter seasons

This study was carried out to investigate the carcass characteristics of Hanwoo (Korean cattle) from different sex conditions, raising altitudes and slaughter seasons. The total number of cattle used in this study was 3608 heads which comprised of 1336 bulls and 1660 steers. The data was analyzed according to sex condition (bull and steer), raising altitude (low: 0–100 m and high: 700–800 m) and slaughter season (spring, summer, autumn and winter). At 24 h post-slaughter, the carcasses were weighed and evaluated for carcass traits according to the Korean carcass grading standard by an official grader. Carcass weight, ribeye area, yield index and grade, and meat color, firmness and maturity scores of carcass from bulls were significantly higher (P < 0.001) than those from steers. Inversely, the backfat thickness, marbling score and quality grade of carcass from steers were significantly higher (P < 0.001) than those from bulls. The maturity score of carcass from a high area was significantly higher (P < 0.01) than that from a low area. The ribeye area of carcass from summer was significantly smaller (P < 0.05) than that from other seasons. The maturity score of carcass from the summer season was highest among that from other seasons and the lowest was that from the winter season. Marbling score and carcass quality grade from the winter season were highest among those from other seasons and the lowest were those from the autumn season. There were no significant interactions between sex condition and raising altitude on carcass traits except the ribeye area. There were significant interactions between sex condition and slaughter season on marbling score and carcass quality grade. There were no significant interactions between raising altitude and slaughter season on all of the carcass traits. There were significant interactions among sex condition, raising altitude and slaughter season on meat color score. It was concluded that sex condition affected muscle and fat depositions on the carcass, raising altitude affected maturity and slaughter season affected ribeye area, maturity and marbling.     

Effect of time of progesterone supplementation on serum progesterone and the conception rate of cooled Holstein heifers during the summer

To investigate the effects of progesterone supplementation at two different times on serum progesterone (P₄) concentration, conception rate and resynchronization of cooled Holstein heifers in summer, 90 heifers were randomly assigned to two groups: (i) heifers subjected to TAI (timed artificial insemination) and progesterone supplementation from days 4 to 14 after TAI (S_1; n = 45); and (ii) heifers under the same TAI protocol as S₁ and progesterone supplementation from days 17 to 22 after TAI (S₂; n = 45). The groups S₁ and S₂ were cooled 10 days before and 21 days after TAI. Respiratory rate, body surface temperature, vaginal temperature and rectal temperature recorded during the experiment were not different (P > 0.05) between S₁ and S₂ groups. Progesterone concentration was not different (P > 0.05) in S₁ compared to S₂. The conception rates on days 30 and 55 were similar between groups (P > 0.05). Progesterone supplementation did not increase either conception rate or concentrations of P₄ in heifers during the summer. Heifers not pregnant to first service in the group S₂ were resynchronized (77.7%) for a second breeding.     

Ovarian follicular dynamics and hormones throughout the estrous cycle in Thai native (Bos indicus) heifers

Relatively few studies have been reported regarding the reproductive physiology of female Thai native cattle. Therefore, the objective of the present study was to evaluate the follicular dynamics and concentrations of follicle stimulating hormone (FSH), estradiol (E2) and progesterone (P4) during the estrous cycle in Thai native heifers (TNH) and to compare obtained results with those of European and Indian cattle breeds previously reported. For the detection of estrus, ovaries of all 20 heifers were examined twice daily (12 h intervals) by ultrasonography for three consecutive estrous cycles. From data of 60 estrous cycles (n = 60 estrous cycles from 20 heifers), it was found that 14 (70%) and 6 heifers (30%) had two (42 estrous cycles collected from 14 heifers) and three follicular waves (18 estrous cycles collected from 6 heifers), respectively. The days when estrus was detected, interovulatory intervals, life‐spans of corpus lutea (CL), and days for growing and regression of CLs were shorter in the two follicular waves than those in the three follicular waves (P < 0.05). In both two and thre follicular waves, larger maximum diameters and higher growth rates of the dominant follicle (DF) in an ovulatory wave were observed than those of the preceding waves without ovulation (P < 0.05). There was a progressive increase in follicular size and FSH and E2 production during follicular growth in each follicular wave. In addition, the FSH and E2 peak concentrations during the ovulatory wave were higher than those of the anovulation waves (P < 0.05). Moreover, although the ovarian follicular dynamic patterns in Thai native heifers were similar to those previously reported for European and Indian cattle breeds, the diameter of the largest preovulatory follicle (OF), subordinate follicles (SF) and CLs were smaller than those in European and Indian cattle breeds. In conclusion, when compared with European and some breeds of Indian cattle, the length of interovulatory intervals was shorter, and the sizes of dominant SF and CLs were smaller in Thai native heifers.     

Physical conditions in a cattle vehicle during spring and autumn conditions in Japan, and reactions of steers to long distance transport

The objective of this study was to investigate transportation conditions and behavioral and physiological responses of beef steers to long distance commercial transport in Japan. In spring (May) and autumn (September), eight (16 in total) Japanese Black × Holstein steers (7.8 ± 0.6 month of age; 310.3 ± 13.9 kg) were transported by truck. The transport distance was 1013.1 km (25 h including lairage periods) comprising 627.6 km (6.4 h) on expressways, 143.5 km (3.5 h) on arterial roads and 242.0 km (10.5 h) by ferry. The loading space of the truck gave a space allowance of about 1.62 m²/head. Internal temperature (±SD) and humidity (±SD) of the truck were 14.7 ± 4.7°C and 72.7 ± 22.4% in spring, 24.4 ± 2.8°C and 70.8 ± 14.4% in autumn. Vibration acceleration (±SD) of the truck in the longitudinal direction was greater in spring (?0.19 ± 0.43 m/s²) than in autumn (?0.15 ± 0.20 m/s²) (P < 0.05). There were no effects of season and driving conditions on the internal noise. Internal airflow velocity (±SD) of the truck was greater in spring (0.75 ± 0.70 m/s) than in autumn (0.45 ± 0.40 m/s) (P < 0.05), and it was greater while moving on expressways (0.77 ± 0.40 m/s) and arterial roads (0.63 ± 0.61 m/s) than when parked (0.16 ± 0.26 m/s) (both P < 0.05). Steers lay down more frequently while moving on expressways than the expected frequency (χ² = 121.9, P < 0.01). Steers were oriented parallel to the direction of travel (to the front cabin: 27.9%; to the tailgate: 23.4%) more frequently than the expected probability (12.5%). Blood glucose concentration, serum ALT activity and plasma cortisol concentration were greater in spring than in autumn (all P < 0.05). Serum pH was higher in autumn than in spring (P < 0.01). Blood glucose concentration was significantly higher at the market before transport, and serum total protein, triiodothyronine and total cholesterol concentrations were also significantly higher at the market and just after transport than 1 week after transport (all P < 0.05). However, the other physiological measurements such as plasma cortisol and blood lactate concentrations, serum pH and heart rate did not change after transport. The results indicate that in Japanese spring and autumn conditions, long distance transport with appropriate conditions including low stocking density and enough lairage time with provision of food and water might not cause severe stress for steers.     

Energy and protein requirements for growth of Holstein × Gyr heifers

There is little information regarding the nutritional requirements for dairy heifers, leading the majority of nutrient requirement systems to consider dairy heifers to be similar to beef heifers. Therefore, we evaluated the muscle protein metabolism and physical and chemical body composition of growing Holstein × Gyr heifers and estimated the energy and protein requirements. We performed a comparative slaughter experiment with 20 Holstein × Gyr heifers at an initial body weight of 218 ± 36.5 kg and an average age of 12 ± 1.0 months. Four heifers were designated as the reference group, and the 16 remaining heifers were fed ad libitum . The 16 heifers were distributed using a completely randomized design in a 2 × 2 factorial arrangement with two roughages (corn silage or sugarcane) and two concentrate levels (30 or 50%) for 112 days. Greater (p  <  0.05) values for fractional rates of muscle protein synthesis, degradation and accretion were observed for heifers that were fed 50% concentrate. The following equations were obtained to estimate the net energy for gain (NE _g) and net protein for gain (NP _g): NE _g (Mcal/day) = 0.0685 × EBW ^0.75 × EBWG ^1.095 and NP _g (g/day) = 203.8 × EBWG  ? 14.80 × RE , respectively, in which EBW is the empty body weight, EBWG is the empty body weight gain and RE is the retained energy. We concluded that increased rates of protein turnover are achieved when a greater quality diet is provided. In the future, these results can be used to calculate the nutritional requirements for growth of Holstein × Gyr heifers after equation validation rather than using the recommendations provided by other systems, which use values developed from beef heifers, to determine the nutritional requirements of dairy cattle.     

Physiological Predictors in Calves of Dairy Breeds: Part 1. Genetic Parameters of Basal and Induced Growth Hormone Secretion

Abstract

Genetic variation in plasma growth hormone (GH) concentration before and after GRF (growth hormone releasing factor) stimulation was studied in young bulls (N=284) and heifers (N=212), the progeny of 53 sires of four dairy and dual-purpose breeds (Danish Jersey, Red Dane, Danish Friesian and Danish Red and White). Male and female calves were reared, fed and tested on separate experimental stations; thus sex, station and feeding were completely confounded effects. The animals were tested at about 9 months of age, after a 24 h fast. GH concentration was measured in serial plasma samples collected for 1 h before and 1 h following intravenous administration of 2.0 ug synthetic GRF(1–29)NH₂/kg live weight^>0.75. Prior to statistical analysis, concentrations were log_e-transformed. Response variables were BASELINE (mean GH in -15, -5 and 0 min samples) and PEAK (mean GH in 10, 15 and 20 min samples). A statistical model taking at least three generations of ancestral relationships into account was used to estimate variance and covariance components for traits in male and female calves by use of restricted maximum likelihood methods.

Heritability of BASELINE was low (0.04 ± 0.12) in males but high in females (0.60 ± 0.16). The heritability of PEAK was high in both sexes (males, 0.42 ± 0.16; females, 0.60 ± 0.16). Genetic correlations between the same trait measured in males and females were low for BASELINE (r _g = 0.32±0.55) but high for PEAK (r _g = 0.82±0.15). Within sex, BASELINE and PEAK were both highly genetically correlated (males, r _g=0.62 ± 0.40; females, r _g= 1.00 ± 0.07).

We conclude that growth hormone concentration is a highly heritable trait in juvenile cattle of both sexes, and that GRF stimulation is benificial to the uncovering of genetic differences among animals.     

Relationships between postnatal plasma oxytocin concentrations and social behaviors in cattle

We examined the associations between natural individual variations in basal oxytocin (OXT) in postnatal cattle and social behavioral traits. At 1, 2 and 6 weeks of age, the basal OXT exhibited individual variability in 20 Holstein heifer calves. Cluster analysis of mean OXT for these time periods obtained two subgroups: high OXT (HOXT; n = 9) and low OXT (LOXT; n = 11). Social behaviors were observed for 2 days at week 6 after introduction into a four‐peer group, and at 10–14 months of age (10 months) immediately and 1 week, 1 month and 5 months after introduction into 11–15 heifers. At week 6, the main effect of the OXT groups was not significant for all social behaviors. At 10 months, there tended to be interactions between the OXT groups and time periods with respect to the frequency of escape behaviors. LOXT heifers exhibited more escape behaviors than HOXT heifers on the first day of the second sociality tests. At 10 months, HOXT heifers exhibited both attacking and affiliative behavior for peers more than LOXT heifers during 5 months after the second social introduction. This suggests that postnatal OXT concentrations may have long‐lasting effects on individual differences among social behavioral traits in cattle.     

Expression of skin color genes in lymphocytes of Karan Fries cattle and seasonal relationship with tyrosinase and cortisol

To evaluate difference in the expression of skin color genes (melanocortin 1 receptor (MC1R) and premelanosome (PMEL)) in lymphocytes during winter and summer season and their correlation with tyrosinase enzyme and cortisol, ten Karan-Fries heifers were selected from National Dairy Research Institute (NDRI) cattle farm. Blood samples were collected from the animals during winter (THI?=?60) and summer (THI?=?83) season at weekly intervals. Relative MC1R and PMEL messenger RNA (mRNA) expression of Karan Fries cattle was found to be significantly (P?P?P?相似文献   

Compliance rate of livestock vehicles with welfare standards, and behavior of feeder cattle at loading ramp

The objective of the present study was to assess cattle welfare during transportation. Vehicle inspection and observation of cattle behavior during loading operations were conducted at two major livestock markets (T and M) in Japan. Market T provided young feeder cattle (Wagyu and cross‐bred aged 6.8–9.0 months) mainly for regions farther than 1500 km. Market M provided young cattle (Wagyu aged 6.6–11.2 month) and calves (crossbred and Holstein aged 0.7–1.5 month) for nearby regions within 500 km. Market T had loading platforms 1.0 m high, whereas market M had partial allocation of platforms and forced most transporters to load cattle from the ground. Vehicles were inspected according to the welfare standards for beef cattle of the RSPCA. Number of vehicles inspected was 36 and 31 in markets T and M, respectively. Cattle hesitations (kneeling down, slipping, balking, backing down, turning around, jumping and eliminating) were observed at the loading ramp. Vehicles inspected at the markets complied with most requirements of the welfare standards, but non‐compliance was found in two requirements: in market M, 71.0% of vehicles had the loading ramp at a >20% incline, whereas 17.1% of vehicles did in market T (P < 0.001). Slope of the loading ramp was steeper in market M than in market T (33.9 ± 17.3% vs. 14.9 ± 8.9%, P < 0.001). Market M had higher proportion of vehicles that did not comply with the requirement ‘Both loading ramps and tail boards must be appropriately designed and covered with litter, to prevent animals from falling off or slipping’ compared with market T (83.9% vs. 17.1%, P < 0.001). Higher frequencies were observed in two kinds of hesitating behavior in market M than in market T (both P < 0.01): mean frequencies (times/head) of slipping and balking were 1.3 ± 1.2 and 2.0 ± 1.8 in market M, and 0.2 ± 0.2 and 0.7 ± 0.5 in market T, respectively. Steeper loading ramp was correlated with higher frequencies of kneeling down (r = 0.53), slipping (r = 0.59), balking (r = 0.45) and backing down (r = 0.42) (all P < 0.05).     

Effect of caudal epidural xylazine on intraoperative distress and post-operative pain in Holstein heifers

Objective To compare the effects of caudal epidural xylazine versus saline on tolerance of paravertebral nerve block and flank surgery and on post‐operative pain in heifers used for a veterinary student training laboratory. Study design Randomized controlled prospective study. Animals Fourteen one‐year‐old, nongravid, healthy Holstein heifers, weighing 360 ± 5 kg. Methods Xylazine (0.05 mg kg^?1) or 0.9% saline (5 mL) was injected using a caudal epidural technique to seven heifers undergoing a flank surgery. Nerve block of the right paravertebral fossa was performed using equal parts of lidocaine 2% and bupivacaine 0.5%. Heart and respiratory rates, rectal temperature, rumination frequency, and appetite were recorded before and at 4, 8, and 24 hours after surgery. Scores were recorded for: tolerance of local anesthesia injections (pre‐operatively), sedation, ataxia and distress (intraoperatively, every 30 minutes), and pain (4, 8, and 24 hours post‐operatively). Results The animals reaction to local anesthetic injection was judged to be less in the xylazine group by both an experienced observer (p < 0.001) and student surgeons (p < 0.01). The xylazine group required less local anesthetic (82.9 ± 13.8 mL) versus the saline group (108.4 ± 19.6 mL, p = 0.035). Intraoperatively, xylazine heifers were more sedated at all times (p‐values from <0.001 to 0.017), were more ataxic for the first 1.5 hours (p‐values from <0.001 to 0.026), and lower in distress at all times (p‐values from <0.001 to 0.007). No difference in post‐operative pain or physiologic variables was found, except immediately post‐operatively, rectal temperature was higher in the xylazine group (39.5 ± 0.3 °C) than in the saline group (38.6 ± 0.2 °C, p < 0.001). Conclusion and clinical relevance Compared with epidural saline, caudal epidural xylazine reduced distress of anesthetic injection and surgical manipulation in heifers and an improvement in animal well‐being was apparent. This effect may have been as a result of sedation. Pre‐operative epidural xylazine did not appear to improve post‐surgical analgesia in our study.