Angus Calves Research Articles

Prediction of Mature Weight and Maturing Rate from Body Measurements Taken on Angus and Charolais Calves at Birth11Published with the approval of the director of the Arkansas Agricultural Experiment Station, manuscript no. 00047.

<h2>Abstract</h2> The objective of this study was to use body measurements taken at birth to predict mature weight (MW) and maturing rate (MR) of mature cows. Measurements for length of rear leg from hook to dewclaw (LL), circumference of forearm (FA), heart girth circumference, body length from point of shoulder to pin bone (BL), width at loin (WL), width at hip, and depth at chest (DC) were taken within 24h of birth on 131 purebred female Angus calves and 39 purebred Charolais female calves in 1992, 1993, and 1994. Fifty-four Angus and 20 Charolais cavles were available for estimates of MW and MR. Stepwise regression determined which traits would be significant predictors of MW and MR. Early BW or ADG (for various intervals up to 1yr of age) were also included in some models. Stepwise regression, including the seven body measurements, resulted in the following equations: MW=−230.12 + 22.54 (LL) +16.38 (FA) + 1.12 (BL) + 30.61 (WL) − 21.66 (DC) and MR=0.10018 − 0.00038 (BL). The R² values were 0.46 and 0.29, respectively. Including early BW or ADG in models for MW did not result in higher R² values, although models with fewer traits included were obtained. Results of this study indicate that body measurements taken at birth may be useful in predicting MW and MR of cows.

Effects of Pre-Weaning Vitamin E, Selenium, and Copper Supplementation on the Performance, Acute Phase Protein Concentration, and Immune Function of Stressed Beef Calves

Abstract Two experiments were conducted to determine the effects of pre-weaning vitamin E, Se, and Cu supplementation on performance and immune response in stressed calves. In Exp. 1, 71 Hereford x Angus calves were individually creep fed: 1) control supplement (CON), 2) control plus 500 IU vitamin E + 0.3 mg Se/kg DM (E), 3) control plus 10 mg Cu/kg DM (CU), or 4) a combination of E and CU treatments (ECU). In Exp. 2, 80 Hereford (Angus calves were individually creep fed: 1) control supplement (CON), 2) control plus 0.3 mg Se/kg DM (SE), 3) control plus 500 IU vitamin E + 0.3 mg Se/kg DM (LOWE), 4) control plus 1000 IU vitamin E + 0.3 mg Se/kg DM (MEDE), or 5) control plus 1500 IU vitamin E + 0.3 mg Se/kg DM (HIE). Treatments continued for 49 (Exp. 1) or 53 d (Exp. 2) prior to weaning. At weaning all calves were transported to feedlot facilities. In Exp. 1, vitamin E tended (P

Differences in susceptibility to gastrointestinal nematode infection between Angus and Brangus cattle in south Louisiana

Breed susceptibility to nematode infection was evaluated in Angus ( Bos taurus) and Brangus ( B. indicus crossbreed) cattle. A cow-calf herd and a yearling replacement heifer herd were monitored during one grazing season. Calves were born in March and were weaned in October. Individual rectal fecal samples were collected monthly from the two herds and processed for fecal egg counts (FEC) and coprocultures. Cow and calf FEC increased from April, reaching maximum values during the summer. Angus cows and calves had significantly ( p<0.05) greater FEC than Brangus cows and calves, and Haemonchus and Cooperia were the predominant genera. Replacement heifer FEC showed a similar pattern with maximum levels during late summer/fall, and Haemonchus was the predominant genus. No significant differences were seen between breeds, however, infection levels were consistently lower in Brangus heifers. Ostertagia was present in cows and heifers only in fall/winter, which is consistent with summer inhibition. The data suggested that cows were an important source of pasture contamination for their susceptible calves and that the Brangus breed was relatively more resistant to infection. The use of B. indicus crossbreeds may help in alleviating reliance on chemical control by reducing the rate of pasture contamination and subsequent infection losses.

Effect of tropically adapted sire breeds on preweaning growth of F1 Angus calves and reproductive performance of their Angus dams.

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.

Ivermectin disposition kinetics after subcutaneous and intramuscular administration of an oil-based formulation to cattle

Slight differences in formulation may change the plasma kinetics and ecto–endoparasiticide activity of endectocide compounds. This work reports on the disposition kinetics and plasma availability of ivermectin (IVM) after subcutaneous (SC) and intramuscular (IM) administration as an oil-based formulation to cattle. Parasite-free Aberdeen Angus calves ( n = 24; 240–280 kg) were divided into three groups ( n = 8) and treated (200 μg/kg) with either an IVM oil-based pharmaceutical preparation (IVM-TEST formulation) (Bayer Argentina S.A.) given by subcutaneous (Group A) and intramuscular (Group B) injections or the IVM-CONTROL (non-aqueous formulation) (Ivomec ®, MSD Agvet) subcutaneously administered (Group C). Blood samples were taken over 35 days post-treatment and the recovered plasma was extracted and analyzed by HPLC using fluorescence detection. IVM was detected in plasma between 12 h and 35 days post-administration of IVM-TEST (SC and IM injections) and IVM-CONTROL formulations. Prolonged IVM absorption half-life ( p < 0.05) and delayed peak plasma concentration ( p < 0.001) were obtained following the SC administration of the IVM-TEST compared to the IVM-CONTROL formulation. No differences in total plasma availability were observed among treatments. However, the plasma residence time and elimination half-life of IVM were significantly longer after injection of the IVM-TEST formulation. IVM plasma concentrations were above 0.5 ng/ml for 20.6 (CONTROL) and 27.5 days (IVM-TEST SC), respectively ( p < 0.05). The modified kinetic behaviour of IVM obtained after the administration of the novel oil-based formulation examined in this trial, compared to the standard preparation, may positively impact on its strategic use in cattle.

Heterogeneity of Variance by Sex in Postweaning Gain of Angus Calves under Different Environment Levels

Heterogeneity of Variance by Sex in Postweaning Gain of Angus Calves under Different Environment Levels

Effect of Heterogeneous Variance by Sex and Genotypes by Sex Interaction on EBVs of Postweaning Daily Gain of Angus Calves

Effect of Heterogeneous Variance by Sex and Genotypes by Sex Interaction on EBVs of Postweaning Daily Gain of Angus Calves

Long-Term Growth after Hypophyseal Stalk Transection and Hypophysectomy of Beef Calves

Hypothalamic hormones regulate episodic and basal secretion of hormones from the anterior pituitary gland that affect metabolism and growth in cattle. This study focused on long-term growth in young calves subjected to hypophysectomy (HYPOX), hypophyseal stalk transection (HST), and sham operation control (SOC). Cross-bred (Hereford x Aberdeen Angus) and Hereford, and Aberdeen Angus calves were HYPOX (n = 5), HST (n = 5), or SOC (n = 8) at 146 ± 2 days of age, whereas another group was HST (n = 5) or SOC (n= 7) at 273 ± 5 days of age. Body weight was determined every 21 days from birth to 1008 days of age. Anterior vena cava blood was withdrawn at 4-day intervals from day 64–360 for RIA of GH, TSH, T4, T3, and LH, and at 20-min intervals for 480 min to determine episodic hormone secretion. Daily feed intake was determined in HST and SOC calves during an 80-day period. Birth weight averaged 35 ± 1 kg (± se) and was 142 ± 4 kg at 126 days and 208 ± 8 kg at 252 days before surgery. From day 146-1008, growth was arrested (P < 0.001) in HYPOX (0.06 ± 0.01 kg/day) compared with SOC (0.50 ± 0.04 kg/day) calves. Growth continued but at a significantly lower rate (P < 0.05) in calves HST at 146 days (0.32 ± 0.07 kg/day) and 273 days (0.32 ± 0.06 kg/day) compared with SOC (0.50 ± 0.09 kg/day). Growth continued to be impaired to 1008 days, but more so in those HST at 146 days (432 ± 43 kg BW) than 273 days (472 ± 5 kg BW) and less (P < 0.05) than SOC (586 ± 37 kg BW). Daily feed intake was consistently less (P < 0.05) in HST compared with SOC calves. Although episodic GH secretion was abolished and peripheral serum GH concentration remained consistently lower in HST (2.4 ng/ml) than SOC (5.5 ng/ml; P < 0.01), the calves continued to grow throughout 1008 days. Peripheral serum TSH concentration was less (P < 0.05) HST compared with SOC calves. There was an abrupt decrease (P < 0.001) in serum T4 (4-fold) and T3 (3-fold) concentration after surgery that remained to 360 days in HST compared with SOC calves. At the time calves were killed, pituitary gland weight was markedly reduced (P < 0.001) in HST (0.18 ± 0.01 g/100 kg BW) compared with SOC (0.54 ± 0.03 g/100 kg BW). Histological examination of pituitary glands from HST calves indicated the persistence of secretory GH and TSH cells in the same areas of the adenohypophysis as SOC calves. Coronal sections of the gland stained with performic acid-Alcian blue-periodic acid-Schiff-orange G, revealed GH and TSH secreting cells in HST calves similar to controls. These results indicate that long-term growth continues, but at a slower rate, after hypophyseal stalk transection of immature calves in spite of complete abolition of episodic GH secretion and consistently decreased basal secretion of GH, TSH, T4, and T3 compared with sham-operated animals. Growth was abolished after hypophysectomy of immature calves in which circulating GH and TSH was undetectable.

Long-term growth after hypophyseal stalk transection and hypophysectomy of beef calves.

Hypothalamic hormones regulate episodic and basal secretion of hormones from the anterior pituitary gland that affect metabolism and growth in cattle. This study focused on long-term growth in young calves subjected to hypophysectomy (HYPOX), hypophyseal stalk transection (HST), and sham operation control (SOC). Cross-bred (Hereford x Aberdeen Angus) and Hereford, and Aberdeen Angus calves were HYPOX (n = 5), HST (n = 5), or SOC (n = 8) at 146 +/- 2 days of age, whereas another group was HST (n = 5) or SOC (n = 7) at 273 +/- 5 days of age. Body weight was determined every 21 days from birth to 1008 days of age. Anterior vena cava blood was withdrawn at 4-day intervals from day 64-360 for RIA of GH, TSH, T4, T3, and LH, and at 20-min intervals for 480 min to determine episodic hormone secretion. Daily feed intake was determined in HST and SOC calves during an 80-day period. Birth weight averaged 35 +/- 1 kg (+/- SE) and was 142 +/- 4 kg at 126 days and 208 +/- 8 kg at 252 days before surgery. From day 146-1008, growth was arrested (P < 0.001) in HYPOX (0.06 +/- 0.01 kg/day) compared with SOC (0.50 +/- 0.04 kg/day) calves. Growth continued but at a significantly lower rate (P < 0.05) in calves HST at 146 days (0.32 +/- 0.07 kg/day) and 273 days (0.32 +/- 0.06 kg/day) compared with SOC (0.50 +/- 0.09 kg/day). Growth continued to be impaired to 1008 days, but more so in those HST at 146 days (432 +/- 43 kg BW) than 273 days (472 +/- 5 kg BW) and less (P < 0.05) than SOC (586 +/- 37 kg BW). Daily feed intake was consistently less (P < 0.05) in HST compared with SOC calves. Although episodic GH secretion was abolished and peripheral serum GH concentration remained consistently lower in HST (2.4 ng/ml) than SOC (5.5 ng/ml; P < 0.01), the calves continued to grow throughout 1008 days. Peripheral serum TSH concentration was less (P < 0.05) HST compared with SOC calves. There was an abrupt decrease (P < 0.001) in serum T4 (4-fold) and T3 (3-fold) concentration after surgery that remained to 360 days in HST compared with SOC calves. At the time calves were killed, pituitary gland weight was markedly reduced (P < 0.001) in HST (0.18 +/- 0.01 g/100 kg BW) compared with SOC (0.54 +/- 0.03 g/100 kg BW). Histological examination of pituitary glands from HST calves indicated the persistence of secretory GH and TSH cells in the same areas of the adenohypophysis as SOC calves. Coronal sections of the gland stained with performic acid-Alcian blue-periodic acid-Schiff-orange G, revealed GH and TSH secreting cells in HST calves similar to controls. These results indicate that long-term growth continues, but at a slower rate, after hypophyseal stalk transection of immature calves in spite of complete abolition of episodic GH secretion and consistently decreased basal secretion of GH, TSH, T4, and T3 compared with sham-operated animals. Growth was abolished after hypophysectomy of immature calves in which circulating GH and TSH was undetectable.

Physiological and parasitological responses to nematode infections of fattening cattle in the Western Pampas of Argentina

The epidemiology of nematode infection was studied in fattening grazing cattle from weaning (April 1994) to market at the end of their second autumn (July 1995). Sixty Aberdeen Angus calves of seven months of age were randomly allocated by weight to two groups: GT, treated every three weeks with doramectin (200 mcg/kg); and GI, an infected group, only treated with fenbendazole (7.5 mg/kg) at weaning and on the 1st of October. The two groups were grazed together on contaminated lucerne pastures until July, on `clean' oat pastures until October and again on contaminated lucerne until the end of the trial. Fecal egg counts (epg), herbage larvae (L 3), serum pepsinogen (Pep) and blood eosinophils (Eo) were evaluated monthly. Eight steers were slaughtered for worm recovery, three in July 1994, three in December 1994 and two in July 1995. Grazing feed intake was estimated by fecal output (chromic oxide method)/1-diet digestibility and to measure non-specific response, Brucella antibodies were detected at 11 and 40 days post-vaccination in early winter. Fecal egg counts, Pep and Eo of GI increased (P<0.01) from April to July when there was a moderate-to-high level of infection. Ostertagia, Trichostrongylus and Cooperia were the predominant genera. By late winter, all parameters decreased on oat `clean' pastures and increased again when cattle returned to moderately infected lucerne. During summer, the parameters measured reflected the negligible numbers of L 3 on pastures until early autumn. At this time, increased numbers of L 3 were followed by a moderate rise ( P<0.01) of epg, Pep and Eo values. During winter, GT showed higher ( P<0.04) Brucella antibody IgG titers while feed intake of GI was 24.9% depressed ( P<0.02). There were total cumulative weight-gain (WG) differences ( P<0.001) between groups (GT=263.1 kg; GI=214.3 kg). During the second autumn, the mean WG of GT steers was 16.6 kg greater ( P<0.04) than that of GI. Vaccination titres against Brucella suggested non-specific depression of immunity, while higher Pep and Eo levels in second-year steers may have reflected hypersensitivity reactions.

Performance of Angus and Brangus cow-calf pairs grazing Alicia bermudagrass and common bermudagrass-dallisgrass pastures.

This research was designed to examine genotype x environment interactions in cow-calf growth performance of grazing animals. Angus and Brangus cow-calf pairs (minimum of six per breed) were allowed to rotationally graze (14-d intervals) treatment pastures from approximately May through early October in each of 2 yr. Treatment pastures contained relatively pure stands of Alicia bermudagrass (AP) or a mixed stand of common bermudagrass and dallisgrass (CDP). Forage allowance was equalized, using "put-and-take" cow-calf pairs, among forage and breed types at the initiation of each 14-d grazing interval. Forage samples were obtained in each paddock at the initiation of each grazing interval. Forage CP concentration was greater (P < .05; 13.5 vs 11.6%) and NDF concentration was less (P < .05; 63.8 vs 70.6%) for CDP than for AP. Daily weight loss was similar for Angus and Brangus cows, but it was greater (P < .05) for cows grazing AP than for cows grazing CDP. Calf ADG during the grazing season was 35% greater (P < .05) for CDP than for AP pastures and was 23% greater (P < .01) for Brangus than for Angus calves. Relative performance of Angus and Brangus cow-calf pairs was consistent between forages; no breed x forage interactions were observed.

The mannosidoses and ceroid-lipofuscinoses: Experimental studies on two types of storage disease

alpha-Mannosidosis of Angus calves was studied both for its veterinary importance and as a model of analogous human lysosomal storage diseases. This study facilitated a similar study in Australia on Swainsona spp. intoxication of livestock in which the toxic principle was shown to be an indolizidine alkaloid, Swainsonine. These genetic and acquired alpha-mannosidoses are compared with beta-mannosidosis. Collectively the study has helped the understanding of the processes of glycosylation and catabolism of glycoproteins. An experiment of nature involving an alpha-mannosidosis chimeric calf born co-twin to a normal calf helped to define the expectations and limitations of bone marrow transplants in this type of storage disease in humans. The inherited ceroid-lipofuscinoses (Batten disease) were studied in an ovine model. Isolation and analyses of the fluorescent accumulated lipopigment denied the dogma of lipid peroxidation current in the 1970s and 1980s. It was shown that in this, and analogous diseases in humans, the dominantly accumulated species was the very hydrophobic protein, subunit c of mitochondrial ATP synthase. Contrary to the adage that this should reflect a disorder of lysosomal proteolysis, there is accumulating evidence that the primary defect resides in mitochondria. Because of its hydrophobic nature, subunit c forms paracrystaline complexes which appear resistant to proteolysis within the lysosomal apparatus.

Effect of Breed on Botanical Composition of Cattle Diets on Chihuahuan Desert Range

Fecal microhistology was used to estimate botanical composition of samples taken from Hereford (N = 11), Angus (N = 11) and Brangus (N = 37) 3 to 5 year-old cows in 3 seasons (October, 1991 and January and July, 1992) and from Hereford (N = 10), Angus (N = 9) and Brangus (N = 34) calves in October. Breed differences in botanical composition of diets and relationships between dam and offspring botanical composition of diets were examined. Breed differences were observed for cows in all 3 seasons and for calves in October. Brangus cows showed greater preference (P < 0.05) for Sporobolus than Hereford cows in October, January, and July. Brangus cows also showed greater preference for Sporobolus than Angus cows in January and July. Brangus and Angus calves showed greater preference for Sporobolus than Hereford calves in October (P < 0.05). Brangus cows had a stronger preference for Yucca and total shrubs in January than either Hereford or Angus cows. Hereford cows and calves had stronger preference for Aristida than either Angus or Brangus in October (P < 0.05). Regression of October calf botanical components on dam botanical components indicated significant relationships for only 2 genera, Aristida (P < 0.01) and Sporobolus (P <0.06). These data suggest that genetic composition of the animal is an important factor determining utilization of key plant species on Chihuahuan desert ranges.

Reliability of a single fecal egg per gram determination as a measure of individual and herd values for trichostrongyle nematodes of cattle

Abstract Objectives To determine precision of a single fecal egg count, to evaluate the necessity of repeated testing to ascertain the number of parasite eggs found per gram of fecal material (EPG) of a given animal, and to infer the number of cattle that must be sampled to estimate the mean EPG value of a given herd. Design Calves born in 4 successive years were tested for 3 consecutive days in May, July, and September to determine their fecal EPG value. Results were analyzed to determine important sources of variance in the EPG values. Animals 427 Black Angus calves. Procedures Nematode EPG values were determined by zinc sulfate flotation of fecal samples taken from the rectum. Variance components were estimated by restricted maximal likelihood procedures. Results The largest source of variation in fecal egg counts arose from differences among calves. Variation associated with sampling within calf was larger than that associated with year of sampling or day when samples were taken. Repeatability of EPG determinations was between 0.4 and 0.7. Conclusions Collection of 3 replicate samples reduced variance associated with a single calf mean by 25 to 30%. Additional replication would further reduce the variance, but at a diminishing rate. To accurately estimate mean EPG for a herd, a randomly drawn sample should be similar in composition to the herd and include at least 1 animal from the high EPG group, which often constitutes 15 to 20% of the calves. To ensure that, on average, 95% of the samples drawn contain 1 or more animals with high EPG, the sample must include 15 to 20 animals within the grazing group under study.

Effect of fungal biomass in alfalfa hay on intake and total tract digestion in growing beef calves.

Two experiments were conducted to determine effects of fungal biomass (FB), as determined by glucosamine analysis, in alfalfa hay on intake and total tract digestion when fed to growing beef calves. Mycotoxins were not detected in hays used for these experiments. A feedlot trial using 40 weaned Angus calves (270.2 +/- 9.7 kg) showed that DM intake was not affected (P > .05) by FB content of the hay diets. No adaptation response was observed when animals with no previous exposure to molded feed were introduced to hay containing various levels of FB. Hematocrit and plasma cortisol levels were not affected (P > .05) by the presence of FB in the hay. Eight steers were used, in two 4 x 4 Latin squares, for intake and total tract digestibility determinations of two alfalfa hays having similar nutrient profiles but differ in FB concentrations. Hays were fed in long or chopped form. Level of FB did not affect (P > .05) DM intake or total tract DM digestibility. Neutral detergent fiber and ADF digestibilities were 5.4 and 3.7 percentage units higher (P < .05), respectively, for hay with a high vs low FB concentration. Forage chopping reduced (P < .05) DM, NDF, ADF, and CP digestibilities; the effect being similar for the two hay types tested. Results suggest that FB concentrations ranging from 2.9 to 5.5 mg/g of DM do not affect DM intake, however, nutrient digestion can be influenced by molding during field wilting or storage.

Forage systems for beef production from conception to slaughter: III. Finishing systems.

Fall-weaned Angus calves grazed or were fed different forages during winter followed by 1) N-fertilized tall fescue (Festuca arundinacea Schreb.) grazed alone, 2) bluegrass (Poa pratensis L.)-white clover (Trifolium repens L.) sequence grazed with tall fescue-red clover (Trifolium pratense L.), or 3) bluegrass-white clover sequence grazed with alfalfa (Medicago sativa L.)-orchardgrass (Dactylis glomerata L.). Heifers were supplemented with grain at 1% of BW from April until slaughter in July. One-half of steers were supplemented with grain at 1% of BW from July until slaughter in October. Remaining steers were fed no grain but were finished on corn silage supplemented with .9 kg of soybean meal per steer daily, from October until slaughter in late January. Including alfalfa-orchardgrass in systems during the finishing phase resulted in higher daily and total gains during the grazing period, and carcasses had more marbling and higher USDA quality grades at slaughter compared with carcasses of cattle on systems using fescue-red clover. Correlation of final weight with carcass characteristics was low (r < .5). Performance and carcass characteristics were influenced as much or more by forage consumed during the previous wintering phase as by forage fed during the finishing phase. Wintering cattle on stockpiled fescue-alfalfa or alfalfa-orchardgrass hay generally resulted in higher BW at slaughter and more desirable carcass characteristics than systems using tall fescue alone or in combination with red clover. This was particularly notable in steers that grazed without grain until October and were finished on corn silage plus supplement. Final BW and carcass characteristics in all cattle were improved by full season grazing followed by feeding corn silage, compared with cattle finished with grain on pasture.

Effect of selection for feedlot gain, breed and age on growth hormone and growth hormone kinetics in bull calves

Average daily gain, basal GH, and plasma GH kinetics following a bolus injection of GH were determined at birth and at 75, 150, 250, 350 and 450 kg BW in 17 Hereford and 19 Angus bull calves. Calves were offspring of two lines within each breed selected for six generations for rapid 168-d feedlot gain on either a roughage or a concentrate diet. These four lines were from a long-term selection study that were being evaluated to determine the effects of selection diet on factors that regulated their growth rate. Hereford calves weighed more (P &lt; 0.01) at birth. Both breeds had similar (P &gt; 0.05) ADG between birth and 450 kg BW. Overall ADG was positively correlated with birth weight within both breeds (P &lt; 0.01). Selection diet had no effect (P &gt; 0.05) on ADG, basal GH, VSS, T1/2, MCR and SR. Compared with Hereford calves, Angus calves had higher MCR (P &lt; 0.05) and SR (P &lt; 0.1) for both diets, and lower basal GH (P &lt; 0.05) for the concentrate diet. Basal GH (P &lt; 0.01), VSS (P &lt; 0.01), T1/2 (P &lt; 0.05), MCR (P &lt; 0.01), and SR (P &lt; 0.01) generally decreased as calf weights (and age) increased. Basal GH and kinetic parameters were correlated with ADG in only a few instances mostly between birth and 250 kg BW. Several GH kinetic parameters obtained between 150 and 450 kg BW were correlated with calf birth weight. We conclude that ADG and GH kinetics are more closely related to calf birth weight than to diet fed during selection for rapid feedlot gain. Key words: selection for gain, Hereford and Angus cattle, bull calves, growth hormone, GH, kinetics

Differences in copper status and copper metabolism among Angus, Simmental, and Charolais cattle

Thirty-eight pregnant Angus, Charolais, and Simmental heifers and their offspring were used to determine whether differences in Cu metabolism existed among breeds. The heifers were fed either 0 or 10 mg of supplemental Cu per kilogram of DM. Calves were born between d 70 and 125 of the 280 d experiment. There were few differences among breeds in plasma Cu concentration and ceruloplasmin activity when heifers were fed supplemental Cu. When heifers were not fed supplemental Cu, Angus heifers had greater (P < .10) plasma Cu concentrations than Simmental heifers from d 0 until 140 and Charolais heifers from d 28 until 140. Angus heifers had greater (P < .10) ceruloplasmin activity than Charolais and Simmental heifers between d 28 and 196. When dams were fed supplemental Cu, Angus calves had greater (P < .10) plasma Cu concentrations than Simmental calves on all days tested and Charolais calves on d 252 and 280. Ceruloplasmin activity of Angus calves in the Cu-supplemented group was greater (P < .10) than that of Charolais calves on d 224 and 280 and Simmental calves from d 224 until 280. Angus calves born to dams not receiving supplemental Cu had greater (P < .10) plasma Cu concentrations and ceruloplasmin activities than Simmental calves on all days tested. Angus calves also had greater (P < .10) plasma Cu concentrations than Charolais calves on d 196 and greater ceruloplasmin activities than Charolais calves from d 168 until 224. Eight Angus and eight Simmental steers were used to evaluate apparent Cu absorption and retention.(ABSTRACT TRUNCATED AT 250 WORDS)

肉用牛群における黒毛和種子牛の下痢症感受性について

The susceptibilities to diarrhea of calves of 4 breeds, Japanese Black, Japanese Red (Kumamoto), Aberdeen Angus and Hereford, were observed in a beef herd in Hokkaido. The incidence rates of diarrhea in those breeds were 79.2, 31.6, 63.3 and 38.3% respectively and there were significantly different (p=0.001) among 4 breeds. Japanese Black and Aberdeen Angus calves tended to be more sensitive against diarrhea than Japanese Red or Hereford. There was no significantly different among 4 breeds in the age in days at the first diarrhea and the period of treatment.Beef cattle calves are mainly reproduced in small farms which keep small numbers of cows in Japan. Though the cost for production should be expected to be decreased, effective methods such as grazing or mass production are not established yet, especially for Japanese Black calves. Calf diarrhea is one of big problems for mass production of beef cattle2). However, there have been few studies of the susceptibility to diarrhea in the grazing environment for Japanese Black calves.In the present study, we observed the susceptibilities to diarrhea of calves of 4 breeds, Japanese Black, Japanese Red (Kumanoto), Aberdeen Angus and Hereford, in a grazing herd.

Relationship of air temperature, relative humidity, precipitation, photoperiod, wind speed and solar radiation with serum insulin-like growth factor I (IGF-I) concentration in angus beef cattle

Eight paternal half-sib Angus calves born in late April and early May, 1988 were used to investigate the potential relationship of serum IGF-I concentration with photoperiod and various weather variables including minimum, maximum and average air temperatures, relative humidity, precipitation, wind speed and solar radiation. To determine IGF-I concentration, blood samples were obtained at birth and then weekly until the calves reached 1 mo of age and biweekly thereafter. Blood sampling continued until the calves reached puberty as determined by progesterone and testosterone assays. Photoperiod and each weather variable were averaged over the 3 d prior to and including the day of blood sampling (4-d average). Data were divided into two periods: (1) birth through the end of the postweaning period and (2) postweaning period only. Serum IGF-I concentrations were analyzed using a model which included the fixed effects of sex and sample number, the random effect of calf nested within sex and the fixed interaction of sex x sample number, in addition to covariates for weight, photoperiod and weather variables. From birth through the end of the postweaning test, none of the weather variables or photoperiod had significant effects on serum IGF-I concentrations when each was fitted separately. For the postweaning period only, cubic regression coefficients for minimum and average temperatures were .0962 ± .0325 ng/ml/°C 3 and .0976 ± .0272 ng/ml/°C 3, respectively (P<.01). The quadratic regression coefficient for relative humidity during the postweaning period was −.2991 ± .1142 ng/ml/% 2 (P<.05). The quartic regression coefficient for wind speed during the postweaning period was −36.435 ± 13.00 ng/ml/(km/hr) 4 (P<.01). Maximum temperature, precipitation, solar radiation and photoperiod did not have significant effects on postweaning serum IGF-I concentrations. Based on these data, we conclude that temperature, humidity and wind speed were contributing factors to variation in serum IGF-I concentrations in postweaned beef calves.