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1.
A public debate has recently arisen, largely surrounding the issue of pain, over whether freeze or hot-iron branding should be the preferred method of permanently identifying cattle. This study addressed that question by quantifying the following accepted measures of distress and pain over a 25-min sampling period: elevated heart rate, concentrations of cortisol, epinephrine, and norepinephrine, and escape-avoidance reactions and vocalizations. Twenty-four dairy cows (15 Holsteins and 9 Jerseys) were assigned to one of three treatments: freeze-branded (F), hot-iron-branded (H), or sham-branded (S), in which a room-temperature brander was applied. Plasma epinephrine and norepinephrine concentrations showed no discernible trends. Plasma cortisol concentrations were elevated in the F and H cows from 5.5 min to 25.5 min postbranding (P = .04). Heart rate, analyzed as a proportion of the prebranding mean, showed that H cows had a greater, more acute, response than did F cows (P = .04), which exhibited a more prolonged response (P = .07). No cows vocalized during branding; however, H cows had a greater escape-avoidance reaction toward branding than did the F and S cows. Both methods of branding produced elevated heart rates and cortisol concentrations indicative of pain sensations. Because the cows exhibited a greater escape-avoidance reaction and heart rate proportions to hot-iron branding, freeze banding would be preferable to hot-iron branding when feasible.  相似文献   

2.
Effects of prepartum fat supplementation of the dam on cold tolerance of calves were determined in two studies. In Exp. 1, 22 F1, crossbred heifers gestating F2 calves received diets containing either 1.7 or 4.7% dietary fat starting at d 230+/-2d of gestation. Safflower seeds (Carthamus tinctorius) containing 37% oil with 79% linoleic acid were the supplemental fat source in isocaloric-isonitrogenous diets. Calves were separated from their dams at birth, fed pooled dairy-cow colostrum, muzzled to prevent sucking, and returned to their dams in a heated (22 degrees C) barn for 3.5 h. At 4 h of age, a jugular catheter was inserted. At 5 h of age, calves were placed in a 0 degrees C room for 140 min and rectal temperatures and blood samples were obtained at 10- and 20-min intervals. Blood was assayed for glucose, cortisol, and cholesterol. In Exp. 2, 18 multiparous, crossbred beef cows bred to Murray Grey sires were randomly assigned to receive diets containing either 1.7 or 3.1% dietary fat starting at 235+/-2 d gestation. Safflower seeds were used as the supplemental fat source in isocaloric-isonitrogenous diets. At d 260 of gestation, premature parturition was induced in one-half of the cows from each diet group by feeding Ponderosa pine (Pinus ponderosa) needles. Experimental protocols were the same as in Exp. 1, except that cold exposure was at 9 degrees C for 200 min. Rectal temperatures were affected in Exp. 1 by time and diet x time (both P < .01) and diet x calf sex (P < .05) and in Exp. 2 by calf age (P < .05), time, and calf age x time (both P < .01). Plasma cortisol concentrations were affected by time (P < .01) and calf sex x time (P < .05) in Exp. 1 and by time ( P < .01) in Exp. 2. Cholesterol concentrations in Exp. 1 were affected by diet x time (P < .05) and in Exp. 2 by time (P < .05). Plasma glucose concentrations were affected in Exp. 1 by diet (P < .05) and in Exp. 2 by calf age, time, and calf age x time (all P < .01). We conclude from Exp. 1 that feeding heifers supplemental fat during late gestation increased glucose concentrations in the newborn calf, resulting in favorable responses in body temperature in the cold-stressed newborns. This increase in substrate availability suggests a potential positive effect on heat generation in newborns during sustained periods of cold stress. In Exp. 2, premature calves had compromised cold tolerance possibly due to impaired shivering or brown adipose tissue thermogenesis.  相似文献   

3.
The effects of ambient temperature and source of exogenous energy (glucose or colostrum) on the ability of newborn Brahman calves to maintain rectal temperature (RT) were determined. All calves were removed from dams within 30 min of birth, before suckling. Calves were catheterized and placed in either a warm (25 degrees C) or cold (5 degrees C) environment for 150 min and given either colostrum or glucose. This resulted in four groups (warm colostrum, n = 7; cold colostrum, n = 7; warm glucose, n = 6; cold glucose, n = 6). Blood samples and RT were obtained at 15-min intervals during warm or cold through 150 min, when calves were removed from cold, and at 180, 240, and 300 min. After 60 min, each calf was given either 1 L of colostrum (38 degrees C) from its dam or glucose (38 degrees C) infusion of 750 mg/kg BW. Plasma glucose concentrations were determined by enzymatic techniques and serum insulin concentrations by RIA. Calves exposed to cold or warm air temperatures had similar declines in rectal temperature from 0 to 60 min. Colostrum-fed, cold calves had a greater (P less than .07) decrease in RT than did colostrum-fed, warm calves from 75 through 150 min; glucose-infused warm and cold calves had intermediate decreases in RT. Plasma glucose increased (P less than .0001) in glucose-infused compared with colostrum-fed calves at 75 min, but glucose-infused calves had lower (P less than .02) glucose levels from 180 to 300 min. Higher (P less than .05) glucose concentrations  相似文献   

4.
Cow size, reproductive traits and calf performance through weaning were evaluated in a range environment for Simmental (S) x Hereford (H) and Angus (A) x H crosses in two-breed rotations and straightbred H. Data were grouped into seven dam breed categories: straightbred Hereford (H), crossbred F1 S x H cows (SH), S x H cows of low percentage H (SHS), S x H cows of high percentage H (HSH), F1 A x H cows (AH), A x H cows of low percentage H (AHA) and A x H cows of high percentage H (HAH). Straightbred H, SH, AH, SHS and AHA cows were mated to H bulls, HSH cows were mated to S bulls and HAH cows were mated to A bulls. Cows in the SHS and AHA groups ranged from 1/4 to 3/8 H and their calves from 5/8 to 11/16 H. Cows within the HSH and HAH groups ranged from 5/8 to 3/4 H and their calves from 5/16 to 3/8 H. Cow age ranged from 3 to 10 yr. Simmental-cross cows were heavier and taller and produced heavier calves at birth and weaning than A-cross. Pregnancy rate, calf birth date and percentage of difficult births did not vary significantly among dam breed groups. Within the A x H and S x H rotations, dam breed group rankings for calf birth weight were inverse to rankings for proportion of H in the breed makeup of the calf.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
Castration in weaned calves is stressful and affects profitability by reducing ADG and increasing susceptibility to disease. This study evaluated the effect of meloxicam, a nonsteroidal anti-inflammatory drug (NSAID), on performance and health of calves received as steers compared with bull calves surgically castrated on arrival at the feedlot. British × Continental bulls (n = 145) and steers (n = 113; BW = 193 to 285 kg) were transported for 12 h in 3 truckloads (d 0), weighed, and randomly assigned to receive either lactose placebo (CONT; 1 mg/kg) or meloxicam (MEL; 1 mg/kg) suspended in water and administered per os, 24 h before castration. On d 1, bulls were surgically castrated (CAST) and steers were processed without castration (STR). Combinations of CONT/MEL and CAST/STR were allocated to 24 pens (6 pens per treatment) of 8 to 14 calves each. Pen was the experimental unit. Plasma meloxicam concentrations at the time of castration (d 1) were determined by HPLC-mass spectroscopy. Pen-level ADG, DMI, and G:F were estimated using BW obtained on d 0, 14, and 28 and weigh-back of feed. Individual animals were classified as sick based on a depression score of ≥2 on a 5-point scale and a rectal temperature of ≥39.8°C. On d 0, 1, and 14, calf chute temperament was evaluated using a 4-point scale. Data were analyzed using generalized linear mixed models and survival curve analyses. Castration reduced pen ADG (P < 0.001) and G:F (P < 0.001) from d 1 to 14, yet no effects (P > 0.45) were apparent by d 28. For all treatment groups, DMI increased with days on feed (P < 0.0001) but was less in CAST compared with STR calves (P < 0.016) throughout the study. From d 15 to 28, ADG increased (P = 0.0011) in CAST but not STR calves, and G:F decreased (P = 0.0004) in STR but not CAST calves. In CAST calves only, MEL treatment reduced the pen-level first pull rate (P = 0.04) and reduced bovine respiratory disease morbidity rate (P = 0.03). The frequency of chute escape behavior was greater on arrival and at castration in CAST vs. STR calves (P < 0.01) but not significantly different at d 14 (P = 0.22). Mean MEL concentrations at castration were no different between treated STR and CAST calves (P = 0.70). Meloxicam administration before castration in postweaning calves reduced the incidence of respiratory disease at the feedlot. These findings have implications for developing NSAID protocols for use in calves at castration with respect to addressing animal health and welfare concerns.  相似文献   

6.
Brahman calves (n = 28) were used to evaluate the effect of environmental temperature during the 1st or 2nd d after birth. Calves were removed from their dams within 30 min of birth (newborn; D0) before suckling or at 20 h of age and fasted for 4 h before treatment (day-old; D1). Calves were placed in either a warm (W; 25 degrees C) or a cold (C; 5 degrees C) environment for 2 h and either maintained in or transferred to, respectively, W for 22 h. Blood samples were collected via jugular catheters at 15-min intervals beginning at initial placement in W or C through 3 h and at 4, 5, 6, 8, 10, 12, 14, 18, and 24 h. Rectal temperature (Tr) was recorded with each sample. Following the 60-min and 12-h samples, each calf was administered 1 liter of colostrum from its dam. Serum or plasma was analyzed for glucose, lactate, plasma urea nitrogen, triglycerides, nonesterified fatty acids, insulin, cortisol, triiodothyronine (T3), and thyroxine (T4). Rectal temperature of D0C calves was lower (P less than .05) than that of other calves from 75 min through 3 h. Insulin, lactate, T3, and plasma urea nitrogen concentrations were not different among all calves. Higher (P less than .01) cortisol and T4 concentrations were observed in D0 than in D1 calves. Cortisol (P less than .008) and nonesterified fatty acid (P less than .05) levels were greater in C than in W calves. All D0 calves had lower (P less than .0001) glucose concentrations than D1 calves until the 12-h feeding.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

7.
Nonpregnant F1 crossbred cows, progeny of either Hereford (H) or Angus (A) dams and sired by Brahman (Bm), Sahiwal (Sw), Pinzgauer (Pz), H, or A sires, were fed to maintain initial weight while rearing Charolais (C)-sired progeny for a period of 126 d in drylot commencing at about 48 d postpartum. Cow-calf pairs were assigned to equalize cow age, calf sex, and breed of cow's dam among three replicate pens of approximately 12 pairs each. Cows and calves were weighed every 2 wk and feed intake was adjusted to minimize change in cow weight. Metabolizable energy (ME) consumption for zero cow weight change was estimated by regression. Milk production was estimated by weight-suckle-weigh at 58, 85, 125, and 170 d of lactation. Calf gain (GAIN, kg) relative to cow weight (CWT1, kg) was higher (P less than .01) for calves from Bm-X (139.5/585) and Sw-X (132.2/534) than for calves from Pz-X (127.2/552) and HA-X (116.9/547) cows. Estimated mean daily production of milk was 7.40, 7.15, 7.28, and 6.37 kg for the Bm-X, Sw-X, Pz-X, and HA-X, respectively. Total cow ME intake (TMEcow) for breed groups ranked (P less than .05) with cow size and milk production, and calf creep-feed intake (FMEcalf) was inversely related to estimated milk intake. Proportion of total feed ME (TMEcow+calf) consumed by calves was higher (P less than .05) for HA-X cows (18%) than for the others (14%). Total efficiency of calf gain in weight (GAIN/TMEcow+calf) was 11% greater (P less than .05) for crossbred cows of Bos indicus X Bos taurus (Bm-X, Sw-X) than for Bos taurus X Bos taurus (Pz-X, HA-X) cows (35 vs 32 g/Mcal) in the 126-d lactation period.  相似文献   

8.
Effects of feeding pregnant dams supplemental dietary fat during the last 55 d of gestation on cold tolerance of newborn crossbred calves with (Piedmontese cross, P, n = 15) or without (Hereford cross, H, n = 16) the muscle hypertrophy allele was determined. Primiparous F1 dams gestating F2 calves of the respective breeds were assigned randomly within breed to receive gestation diets containing either 2.2 (Low Fat; LF) or 5.1% fat (High Fat; HF). Safflower (Carthamus tinctorius L.) seeds containing 37% oil with 79% linoleic acid were the supplemental fat source in diets formulated to be isocaloric-isonitrogenous. At parturition, calves were separated from their dams, fed 38 degrees C pooled dairy cow colostrum (30 mL/kg BW), muzzled to prevent suckling, and returned to their dams in a heated (22 degrees C) room for 3.5 h. At 4 h of age (birth = 0 h), a catheter was inserted into the jugular vein. At 5 h of age, calves were placed in a 0 degrees C room for 140 min, and rectal temperatures and blood samples were obtained at 10- and 20-min intervals. Blood was assayed for cortisol and glucose. Rectal temperature was affected by diet (P<.05), time, diet x time, and breed x time (P<.01 for time and the interactions). Cortisol and glucose concentrations were not affected by diet, breed, or the diet x breed interaction, but they were affected by time, breed x time (both P<.01), and diet x time (P = .06). Calves from HF dams had higher rectal temperatures than calves from LF dams, and the HF calves maintained higher rectal temperatures throughout cold exposure. Cortisol concentrations were lower (P = .06) in calves from HF dams, and these calves had more (P = .06) glucose available for metabolic heat production than calves from LF dams. Piedmontese-cross calves maintained higher (P<.01) rectal temperatures and had higher cortisol and glucose (both P<.01) concentrations than did H-cross calves. We conclude that feeding dams supplemental fat during late gestation increased heat production in newborn calves and potentially could increase calf survival; calves with muscle hypertrophy may have a different ratio of shivering vs nonshivering thermogenesis due to differences in body composition or relationships among uncoupling proteins.  相似文献   

9.
A study was conducted to determine the effect of the milk-ejection reflex on exogenous gonadotropin releasing hormone (GnRH)-induced release of luteinizing hormone (LH) after short-term calf removal. Twenty-four postpartum multiparous beef cows were assigned randomly to groups arranged in a 2(3) factorial arrangement. Factors consisted of two levels of suckling [suckled (S) or nonsuckled (NS)], treatment with GnRH [saline (C) or 200 micrograms GnRH] and days postpartum (d 1 and 14). Dams were isolated from their calves for 4 h on d 1 and 14 postpartum. At the end of 4 h dams were reunited with their calves in S + C and S + GnRH groups, while dams of calves in NS + C and NS + GnRH groups remained separated an additional 2 h. Cows were injected iv with saline or GnRH following the 4-h isolation period, 5 min after calves had begun suckling or nuzzling the udder. Sera from jugular blood samples collected 15 min prior to the end of the 4-h isolation period, immediately prior to injection (0 h) and at 15 min intervals thereafter for 120 min were analyzed for LH. Serum concentrations of LH in control cows did not differ due to suckling or stage of the postpartum period and averaged 2.3 +/- .1 ng/ml. Pituitary response to GnRH was determined by computing the rate of LH release. Rate of LH release (ng LH.ml-1.min-1) in response to GnRH on d 14 was greater (P less than .001) than on d 1 in both suckled and nonsuckled groups (S + GnRH, 37.1 +/- 3.9 vs 18.3 +/- 5.0; NS + GnRH, 34.7 +/- 5.9 vs 14.5 +/- 1.1). However, GnRH-induced release of LH did not differ between suckled and nonsuckled cows on either d 1 or 14 postpartum. These data indicate that response of the bovine pituitary to GnRH during the postpartum period is not influenced by the act of suckling but is enhanced with time after parturition.  相似文献   

10.
Our objectives were to examine the effects of added fat in late-gestation cow diets on neonatal response to cold. In Exp. 1, pregnant fall-calving heifers received control (n = 5), safflower seed (n = 5), or whole cottonseed (n = 5) diets. The hay-based, isonitrogenous, and isocaloric diets, fed for 47 d prepartum, contained 1.5, 4.0, and 5.0% fat for control, safflower, and whole cottonseed diets, respectively. At calving, calf BW and vigor score, as well as fat, lactose, and IgG in colostrum were not affected (P > 0.30) by diet. Heifers fed the safflower diet tended to have greater colostral solids (P < 0.10) than heifers fed the control or whole cottonseed diets. At 6.5 h of age, calves were placed in a 5 degrees C cold room for 90 min. Calf vigor, shivering, body temperature, and blood samples were taken every 15 min. During cold stress, calf body temperature decreased 0.7 degrees C (P < 0.03). Across all diets, shivering and serum glucose concentrations increased (P < 0.05), whereas calf vigor and cortisol concentrations decreased (P < 0.02) during cold exposure. In Exp. 2, pregnant spring-calving cows (n = 98) received a control (n = 47) or whole cottonseed (n = 51) supplement. Hay-based diets fed for 68 d prepartum contained 2.0 and 5.0% fat for control and whole cottonseed diets, respectively. Calf BW, vigor, shivering, dystocia score, time to stand, time to nurse, serum glucose concentrations, and serum IgG were not affected (P > 0.50) by diet. Between 30 and 180 min, body temperature of calves from dams fed the whole cottonseed supplement decreased (P < 0.05) more than calves from dams fed the control supplement. Serum glucose concentrations in calves were not affected by diet (P > 0.30). Serum cortisol concentrations tended (P < 0.09) to be greater for calves from dams fed whole cottonseed than control calves. When ambient temperature was < 6 degrees C, calves born to dams fed whole cottonseed had greater (P < 0.05) BW, tended (P < 0.1) to stand earlier, and had greater serum IgG concentrations. We conclude that calves from dams fed high-fat diets containing safflower or whole cottonseed respond similarly to cold stress, but these responses may not be consistent with greater cold resistance. In addition, high-fat dietary supplementation of late-gestation cows may only be beneficial during calving seasons with prolonged cold weather.  相似文献   

11.
The literature indicates that sire breed of calf influences beef calf performance. However, there is little information concerning sire breed of calf effects on reproduction in beef cows. In this experiment, Angus (A), Brahman (B), or Tuli (T) bulls were bred to 136 Brahman (B) cows to examine sire breed of calf influence on peripartum hormone profiles and the length of postpartum anestrus. Cows were bled from 7 d prepartum to 28 d postpartum to determine peripartum hormone concentrations. Cows carrying AB calves had greater (P < 0.05) prepartum estradiol-17β concentrations than did cows carrying BB and TB calves. Prepartum and postpartum progesterone concentrations did not differ between cows with AB, BB, and TB calves. Cows with TB calves had lower (P < 0.01) 13,14-dihydro-15-keto-prostaglandin F2 (PGFM) concentrations than did cows with AB and BB calves during the early postpartum period. Adjusting for birth weight removed the sire breed of calf effect on postpartum PGFM concentrations, but not prepartum estradiol-17β. Postpartum anestrus was shorter (P < 0.05) for cows nursing BB calves (84 ± 6 d) than for cows nursing AB (101 ± 6 d) or TB calves (110 ± 7 d). Adjustment for estradiol or PGFM concentrations did not reduce sire breed of calf effects on the length of postpartum anestrus. Further work is needed to determine how calf genotype may modulate the postpartum reproductive function of the dam.  相似文献   

12.
Twelve anestrous, postpartum beef cows were used to determine the effect of calf removal on the effect of naloxone on serum luteinizing hormone (LH) concentrations. On d 1, six cows were injected iv with saline and six with 200 mg naloxone dissolved in saline. Blood samples were taken at 15-min intervals for 2 h before and 2 h after naloxone or saline administration. At the beginning of blood sampling, calves were removed from three cows in each treatment. At 48 h after calf removal (d 3), all cows were injected iv with 200 mg naloxone and blood samples were collected as on d 1. On d 1, naloxone treatment increased (P less than .01) serum LH concentrations from 1.2 +/- .3 ng/ml at time 0 to 4.3 +/- .6 ng/ml and 4.7 +/- .8 ng/ml at 15 and 30 min, respectively. Injection of saline had no effect on serum LH concentrations. Forty-eight-hour calf removal increased (P less than .01) serum LH concentrations in five of six cows (1.7 +/- .8 vs 4.4 +/- 1.2 ng/ml). Naloxone treatment failed to increase serum LH concentrations in these cows. Injection of naloxone increased (P less than .01) serum LH concentrations in the one cow that did not exhibit an LH increase after calf removal and in six cows whose calves were not removed (1.4 +/- .2 vs 4.4 +/- .5 ng/ml). The present study provides additional evidence that endogenous opioids regulate LH in the postpartum beef cow. We hypothesize that suckling stimulates an opioid inhibition of LH secretion and removal of the suckling stimulus removes the opioid inhibitory tone.  相似文献   

13.
October pregnancy rate, calf survival to weaning, weaning age, weaning rate and actual kg of calf weaned/cow exposed were determined in a 4-yr study involving 880 matings of Angus (A), Hereford (H) and Charolais (C) sires to A, H, C and Brown Swiss (BS) dams. Cows were mated in single-sire herds for 45 or 60 d under pasture conditions; heifers were bred to produce their first calf at 3 yr of age. Pregnancy rate of lactating dams was 9.4% higher (P less than .01) than for non-lactating dams. Pregnancy rates for straightbred matings were 87.5%, 80.6% and 75.4%, respectively, for A, H and C groups (P less than .05). No differences (P greater than .10) due to sire breed were found for any of the traits studied except for calf age at weaning. Calves from C sires were younger (P less than .01) at weaning than calves from H and A sires. Breed-of-dam differences (P less than .05 to P less than .01) were found for all traits studied except calf survival rate. All BS dams produced crossbred calves and had lower pregnancy and weaning rates (both P less than .01), calves were younger at weaning (P less than .05), had lower kg of calf weaned/cow exposed (P less than .05) than for beef-breed dams producing crossbred calves. Crossbred calves from BS dams were 4.9, 11.0 and 3.4 d younger (P less than .05 to P less than .01) at weaning, respectively, than crossbred calves from H, A and C dams.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

14.
Seven hundred fifteen crossbred (primarily British) calves purchased in southern Oklahoma and northern Texas auction barns were received at the Willard Sparks Beef Research Center, Stillwater, OK, and used to study effects of duration (days) of vitamin E feeding during a 42-d receiving period on animal performance, health, and serum cholesterol and vitamin E concentrations. Upon arrival, calves were blocked by load (seven loads), sorted by BW (light, n = 4 pens per load; and heavy, n = 4 pens per load), and assigned randomly to one of four dietary treatments (n = 2 pens per load; 14 pens per treatment). Experimental diets were formulated to provide 2,000 IU.calf(-1).d(-1) of supplemental vitamin E (dl-alpha-tocopherol acetate) for 0 (CON), 7 (E7), 14 (E14), or 28 (E28) d. Vitamin E was delivered in a pelleted supplement that was added to the basal diet in decreasing concentrations as DMI increased (2.0 kg of DMI = 6%; 4.0 kg of DMI = 4%; and 6.0 kg of DMI = 2%). Serum samples were collected on d 0, 14, 28, and 42 for determination of cholesterol, alpha-tocopherol (d 0, 28, and 42), and antibody (IgG) concentrations. Duration of vitamin E supplementation did not affect ADG (0.98 kg/d; P = 0.56) or G:F (0.189; P = 0.87). Serum cholesterol concentrations decreased (day effect; P < 0.001) for all treatments from d 0 (average = 127 mg/100 mL) to 14 (average = 62 mg/100 mL). Serum alpha-tocopherol decreased (day effect; P < 0.001) from d 0 (5.2 microg/mL) to 28 (1.8 microg/mL); however, on d 28, a greater (P < 0.001) serum alpha-tocopherol concentration was observed for E28 (3.4 microg/mL) calves than for CON (1.1 microg/mL), E7 (1.2 microg/mL), or E14 (1.5 microg/mL) calves. Respiratory disease was diagnosed in 64.6% of calves in this study. Medical costs were less (P = 0.08) for calves fed vitamin E for 28 d (4.88 dollars/calf) than for calves fed the control diet (6.29 dollars/calf). Carcass characteristics were not affected (P = 0.19 to 0.88) by dietary treatments. Supplemental vitamin E formulated for 2,000 IU.calf(-1).d(-1) had little influence on performance and overall health status of calves under our experimental conditions; however, the increased serum concentrations of alpha-tocopherol when vitamin E was fed for 28 d suggests that any potential effects of vitamin E on health status might be time-dependent.  相似文献   

15.
Experiments were conducted to investigate the effects of the presence of a trainer cow on behavior, performance, health, and feeding patterns of newly weaned beef calves. In Exp. 1,252 weaned calves (270+/-18 kg) were allocated to 22 pens (11 to 15 calves per pen). A trainer cow was randomly assigned to each of 11 pens. Calves were weighed prior to feeding on d 0, 3, 7, 14, 21, and 28. Rectal temperatures were taken on each of these days (except d 28) and blood samples were collected on d 0, 3, and 7 and subsequently analyzed for serum haptoglobin and leukotoxin antibody titers. Instantaneous scan observations of calf behavior were made at 10-min intervals between 0730 and 1730 on d 1, 2, 4, 5, and 6. A similar protocol was used in Exp. 2, in which 297 calves (258+/-17 kg) were allocated to 24 pens. Blood analyses included haptoglobin, white blood cell counts (WBC), and neutrophil:lymphocyte (NL) ratios. In Exp. 3, the above protocol was followed and patterns of feed bunk attendance of individual calves were also monitored using radio frequency identification by passive transponder ear tags. Trainer cows did not influence (P > .10) calf rectal temperatures, requirements for antibiotic therapy, WBC, NL ratios, or leukotoxin antibody titers. Pooled across treatments, NL ratios were lower (P < .01) on d 0 (.31) than on d 3 (.36) or d 7 (.39). Although differences in weight gain were detected in some periods within the three experiments, there were no differences (P > .10) overall (d 0 to 28). Trainer cows did not affect (P > .05) frequency or duration of bunk visits by the calves. Averaged across treatments, frequency and duration of bunk visits increased (P < .001) from 9.6 visits/d and 56.7 min/d between d 0 and 3 to 12.3 visits/d and 108.9 min/d between d 15 and 21. The number of calves observed eating during scan sampling observations also increased from 16.4% on d 1 to 25% on d 4 (P < .10) and 29% on d 5 and 6 (P < .05). More (P < .05) calves were observed lying on d 1 (41.7%) and d 2 (45.3%) than on d 4 (37.5%), d 5 (34.8%), or d 6 (36.2%). With a trainer cow present, fewer (36.7% vs 41.5%; P < .001) calves were observed lying and more (11.7% vs 10.2%; P = .08) were observed walking than when no cow was present. Trainer cows did not improve calf health, time spent at the feed bunk, or performance of newly weaned calves.  相似文献   

16.
The objective of this study was to determine the effect of tropically adapted sire breeds on preweaning growth performance of F1 calves and on reproductive performance of their Angus dams. Angus (A) cows were bred in two consecutive years (1992 and 1993) by AI using semen from Brahman (B; Bos indicus; n = 10), Senepol (S; Bos taurus; n = 10), and Tuli (T; Sanga; n = 9) bulls. A total of 82 B x A, 85 S x A, and 91 T x A calves were born. The statistical model included the fixed effects of year, sire breed, calf sex, sire breed x calf sex, and cow parity and the random effect of sire within sire breed. Birth weight, weaning weight, 205-d adjusted weaning weight, ADG from birth to weaning, and hip height at weaning were greater (P < .001) for B x A calves than for S x A or T x A calves. Greater differences were detected between sexes for B x A than for S x A and T x A (for all traits sire breed x calf sex, P < .05). Sire breed affected (P < .01) the percentage of unassisted calvings (B x A, 87%; S x A, 98%; and T x A, 100%) and tended (P < .10) to affect the percentage of calves that survived until weaning (B x A, 90%; S x A, 94%; and T x A, 98%). Sire breed of calf did not affect (P > .10) length of gestation, and sire breed did not affect the interval from calving to first observed estrus or pregnancy in Angus dams. These results demonstrate that preweaning growth performance of B x A calves was greater than that of either S x A or T x A calves. However, use of Brahman sires on Angus dams led to calving problems and tended to reduce the percentage of calves that survived until weaning. Thus, heavier weaning weights of B x A calves would be an advantage for cow-calf producers marketing calves, but heavier birth weights and calving difficulty attributed to Brahman sires would be a disadvantage.  相似文献   

17.
Forty crossbred steers (Brahman x English) were categorized into two groups: 1) early weaned (EW; n = 20); and 2) normal weaned (NW; n = 20). Calves were 89 and 300 d of age at the time of EW and NW, respectively; SEM = 4.4. Early-weaned calves were kept on-site (University of Florida, Ona), provided supplement (1% of BW), and grazed on annual and perennial pastures until NW. At the time of normal weaning, all calves were loaded on a commercial livestock trailer and transported to the North Carolina State University Research Feedlot in Butner (approximately 1,200 km). Upon arrival, calves were stratified by BW and randomly allotted to four pens per weaning age treatment. Individual calf BW and blood samples were collected at the time of normal weaning, on arrival at the feedlot (d 1; 24 h following weaning), and on d 3, 7, 14, 21, and 28 of the receiving period. Individual BW was collected at the start and end of the growing and finishing periods, and feed intake by pen was measured daily. As an estimate of stress during the receiving period, plasma was collected and analyzed for the acute-phase proteins, haptoglobin and ceruloplasmin. Early-weaned calves were lighter (P = 0.03) at normal weaning than NW calves (221 vs. 269 kg; SEM = 10.6). By d 28, EW calves tended (P = 0.12) to be lighter than NW calves (242 vs. 282 kg, respectively). Gain:feed was improved for EW compared with NW calves during both the receiving (G:F = 0.157 vs. 0.081) and growing (0.159 vs. 0.136) periods. There tended (P < 0.10) to be weaning age x day interactions for each acute-phase protein. Ceruloplasmin concentrations increased in NW, but not EW calves, and peaked on d 7 (27.6 and 34.2 mg/100 mL for EW and NW calves, respectively; P < 0.05). Haptoglobin concentrations increased in both groups and were greatest (P < 0.05) in NW calves on d 3 (7.63 vs. 14.86 mg of haptoglobin/hemoglobin complexing/100 mL). No differences in ADG or G:F were detected during the finishing phase; however, overall G:F was improved (P = 0.03) for EW vs. NW calves (0.155 vs. 0.136). Carcass measures, including backfat thickness, USDA yield grade, marbling score, and LM area, did not differ between treatments. These data imply that EW calves, which are maintained onsite before shipping, may be more tolerant to the stressors associated with transportation and feed yard entry. Early weaned calves, managed within the system described in this study, may have improved G:F.  相似文献   

18.
Two experiments were conducted to determine whether the supplementation of Cu in the organic or inorganic form to 2-yr-old cows, before and after calving, affects reproduction rate, calf health and performance, passive transfer of immunoglobulin, or liver and serum Cu concentrations compared with unsupplemented controls. Cows (n = 75 in 1997; n = 120 in 1998) were randomly assigned by estimated calving date and body condition score to one of three treatments: 1) Control, control; 2) Inorganic, inorganic Cu supplement (200 mg Cu from CuSO4); 3) Organic, organic Cu supplement (100 mg Cu from AvailaCu). In 1998, a fourth treatment was added; 4) CU-ZN, organic Cu and Zn (400 mg Zn from AvailaZn in the Organic diet). Cows were fed a hay-based diet and individually fed supplements for approximately 45 d before and 60 d after calving (approximately January 15 to May 15 each year). Liver biopsies were obtained from cows before supplementation began, and from cows and calves at 10 and 30 d after calving. Blood samples were obtained from both cows and calves at calving, and colostrum samples were collected for IgG and mineral content. Cow liver Cu concentrations before supplementation began were 58 mg/kg in 1997 and 40 mg/kg (DM basis) in 1998. By 10 d after calving, liver Cu concentrations of Control cows had decreased (P < 0.05) to 24 mg/kg (Cu deficient) in both years, whereas liver Cu concentrations of Cu-supplemented cows increased (P < 0.05) in both years. Calf liver Cu concentrations at 10 d of age were similar (P > 0.10) for all treatment groups. No differences (P > 0.10) were found in colostrum Cu concentrations, or in calf health among treatments. No differences (P > 0.10) were found in cow BW change, calf serum Cu concentrations, calf weaning weights, or in cow 60-d pregnancy rates among treatments in either year. In 1998, cows in the Organic group had higher (P < 0.05) 30-d pregnancy rate than Control cows. Neither serum samples nor placental tissue were reliable indicators of Cu status in cows. Feeding supplemental Cu (either inorganic, organic, or organic with extra Zn) to cows with liver Cu concentrations of approximately 50 mg/kg before calving did not improve cow 60-d pregnancy rates or the health and performance of their calves when compared with unsupplemented cows.  相似文献   

19.
Effects of calving season and finishing system on forage and concentrate consumption and carcass characteristics of calves were compared. In each of 3 yr, two replicates of three growing and finishing systems were compared including 1) spring calves finished on a high-grain diet in a feedlot immediately post-weaning (WF); 2) spring calves backgrounded on a hay-corn gluten diet over winter for 179 +/- 18 d after weaning, grazed for 98 +/- 9 d in cool-season grass-legume pastures, and finished on a high-grain diet in a feedlot (SGF); and 3) fall calves backgrounded on a hay-corn gluten feed diet over winter for 69 +/- 31 d after weaning, grazed for 98 +/- 9 d in cool-season grass-legume pastures, and finished on a high-grain diet in a feedlot (FGF). During the grazing phase, calves on the SGF and FGF treatments were equally stocked with spring-calving cow-calf pairs before grazing by pregnant fall-calving cows in a first-last rotational stocking system at a rate of 1.9 standard livestock units/ha. As designed, retained calves in the FGF system spent 110 fewer days in the drylot during backgrounding than retained calves in the SGF system (P = 0.01), resulting in less feed provided during winter. A greater (P < 0.01) quantity of hay was fed to SGF calves after weaning over winter (1,305 kg of DM per calf) than the quantity fed to FGF calves (305 kg of DM per calf). Quantity of grain (including commercial starter) fed to SGF calves after weaning did not differ (P = 0.28) from that fed to FGF calves (126 vs. 55 kg of DM per calf); however, calves in the FGF system required 80 and 71 kg of DM per calf more concentrate to finish to an equivalent external fat thickness compared with SGF and WF calves, respectively (P = 0.02). Average daily gains in the feedlot were greater (P < 0.01) for SGF and FGF calves than for WF calves during all 3 yr. There were no differences (P = 0.69) in carcass quality grades among calves in all groups, but SGF calves had greater (P < 0.01) hot carcass weight and LM area measurements at slaughter than FGF or WF calves. Although calves in the FGF system were 25 kg lighter than calves in the WF system at slaughter (P = 0.03), and had a lower dressing percent (P = 0.03), other carcass characteristics did not differ between these two groups. Lower stored-feed requirements and similar carcass quality characteristics made retention of a fall calf crop advantageous over retention of a spring calf crop for use as stocker animals before finishing.  相似文献   

20.
Although Se is essential for antioxidant and thyroid hormone function, factors influencing its requirement are not well understood. A survey and two experiments were conducted to determine the influence of cattle breed and age on selenoprotein activity and the effect of maternal Se supplementation on cow and calf selenoprotein activity and neonatal thyroid hormone production. In our survey, four cowherds of different ages representing three breeds were bled to determine the influence of breed and age on erythrocyte glutathione peroxidase activity (RBC GPX-1). All females were nonlactating, pregnant, and consumed total mixed diets (Holstein) or grazed pasture (Angus and Hereford). In our survey of beef breeds, yearlings had greater average RBC GPX-1 activity than mature cows. In Exp. 1, neonatal Holstein heifers (n = 8) were bled daily from 0 to 6 d of age to determine thyroid hormone profile. An injection of Se and vitamin E (BO-SE) was given after the initial bleeding. Thyroxine (T4) and triiodothyronine (T3) concentrations were greatest on d 0 and decreased (P < 0.05) continuously until d 5 postpartum (156.13 to 65.88 and 6.69 to 1.95 nmol/L, d 0 to 5 for T4 and T3, respectively). Reverse T3 concentrations were 3.1 nmol/L on d 0 and decreased (P < 0.05) to 0.52 nmol/ L by d 5. In Exp. 2, multiparous Hereford cows were drenched weekly with either a placebo containing 10 mL of double-deionized H2O (n = 14) or 20 mg of Se as sodium selenite (n = 13). After 2 mo of treatment, Se-drenched cows had greater (P < 0.01) plasma concentrations than control cows (84.92 vs. 67.08 ng/mL), and at parturition, they had plasma Se concentrations twofold greater than (P < 0.05) control cows (95.51 vs. 47.14 ng Se/mL). After 4 mo, cows receiving Se had greater (P < 0.05) RBC GPX-1 activity than controls; this trend continued until parturition. Colostrum Se concentration was twofold greater (P < 0.05) in Se-drenched cows than control cows (169.97 vs. 87.00 ng/mL). Calves born to cows drenched with Se had greater (P < 0.05) plasma Se concentration, RBC GPX-1, and plasma glutathione peroxidase activity on d 0 compared with calves born to control cows. By d 7, no differences in plasma glutathione peroxidase activity in calves were observed. Maternal Se supplementation did not influence calf thyroid hormone concentrations. Selenium provided by salt and forages is not adequate for cattle in Se-deficient states.  相似文献   

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