Angus Calves Research Articles

Anthelmintic efficacy of febantel paste in naturally infected calves

The purpose of the present study was to verify results of the lowest dose (5 mg kg −1) of febantel evaluated in an earlier trial in which there were no differences in efficacies of three dose rates (5, 7.5 and 10 mg kg −1 body weight) against natural gastrointestinal nematode infections of cattle. Fourteen Angus calves (mean weight and age of 155 kg and 525 days, respectively), from the same farm, with relatively heavy (mean of 448 eggs g −1 feces (epg)) parasite burdens were selected. After an adjustment period of 8 days in drylot, beginning on 25 July, seven calves were treated with a 45.5% paste formulation of febantel. On Day 7 post-treatment, calves were necropsied for determination of residual worms. Rectal fecal samples were obtained prior to adjustment, at treatment, 5 days post-treatment and at necropsy. On both Day 5 post-treatment and at necropsy a mean of less than 1 epg was recovered from treated calves compared with 765 and 1566 epg, respectively, in control calves. Worms counts at necropsy revealed an efficacy of 98.5% against all adult abomasal worms ( Haemonchus placei, 100%, P < 0.02; Trichostrongylus axei, 99.4%, P < 0.0001; Ostertagia ostertagi, 90.5%, P < 0.0002). Treatment was 100% efficacious against adult small and large intestinal worms. However, numbers of Bunostomum phlebotomum, O. radiatum and Trichuris spp. recovered in the control calves were too low to enable a reliable test of drug efficacy. Treatment was not effective against either mucosal or luminal fourth stage larvae of abomasal O. ostertagi. Efficacy against adult abomasal and intestinal worms was 98.6% in the present study compared with 98.8% in the previous study. Thus, there was no change in the efficacy of febantel against adult worms in calves grown on the same farm after a 5-year period has passed, indicating that no resistance against anthelmintics had developed during that time.

BLOOD COMPOSITION IN HEREFORD AND ANGUS BULLS FROM LINES SELECTED FOR RAPID GROWTH ON HIGH-ENERGY OR LOW-ENERGY DIETS

Angus and Hereford bull calves were obtained from lines of cattle selected for 18 yr for rapid post-weaning gain on high-energy or low-energy diets. After weaning they were given a common diet consisting of 70% barley-based concentrate and 30% roughage. Bulls whose ancestors were selected on the high-energy diet had lower levels of cholesterol and albumin in the blood than bulls whose ancestors were selected on the low-energy diet. Blood insulin, growth hormone and energy substrates were not affected by differences in the nature of the selection diets and this accords with absence of effect of selection diet on rate, efficiency or composition of gain. The significance of the selection effects on cholesterol and albumin levels in blood is unknown. Key words: Angus, Hereford, bulls, blood, composition, selection

Evaluation of eleven cattle breeds for crossbred beef production: performance of progeny up to 13 months of age

ABSTRACTEleven sire breeds were evaluated in New Zealand from the performance of their calves at two sites using Aberdeen-Angus cows, and at a third site using Angus and Hereford cows. The experiment was carried out over 5 years, generating a total of 4519 calves by 161 different sires. There were seven recently imported sire breeds, Blonde d'Aquitaine, Charolais, Chianina, Limousin, Maine Anjou, Simmental (including strains from four countries) and South Devon, and four local breeds, Angus, Friesian, Hereford and Jersey. Overall, 92% of calves survived at birth and through to weaning, with a range from 86% for the Charolais sire breed to 96% for the Friesian and Jersey breeds. The proportion of calves (from cows aged 3 years and over) experiencing birth difficulty averaged 8·6% and ranged from 17·7% for the Charolais, 15·1% for the Chianina and 13·7% for the Maine Anjou, to 2·3% for the Hereford and 0·9% for the Jersey. Birth weights by sire breed had a range of 7·2 kg, proportionally 0·23 of the mean for the Hereford × Angus cross. The birth weights of calves by imported sire breds were greater than those of calves sired by local breeds by 4·7 kg. Sire breeds were ranked in approximately the same order for the weights of calves at weaning (5 months of age) and at 13 months of age. As a proportion of the mean for the Hereford × Angus crosses, there was a range due to sire breed of 0×17 for weaning weight and 013 for 13-month weight. As a group, the imported sire breeds had calves with 13-month weights 11·5 kg heavier than Hereford × Angus or 250kg heavier than straightbred Angus calves; proportionally these advantages in weight were 005 and 011, respectively. There was no evidence of any major interaction between sire breed and location. The heritability estimates ranged from 0·01 to 0·05 for calving difficulty and survival traits, from 0·13 to 0·33 for live weights and from 0·06 to 0·12 for pre-weaning live-weight gains. For gestation length the estimate was 0·48.

Bovine Serological Response to a Recombinant BPV-1 Major Capsid Protein Vaccine

Four of five groups of Holestine by Angus calves (5 calves/group) were immunized with different formulations of a recombinant BPV-1 DNA vaccine using a BPV-1 major capsid:B-galactosidase fusion protein as the immunogen. Group 5 was not vaccinated. Vaccinated calves received the vaccine on days 0 and 21 of the trial, and calves from all five groups were challenged intradermally with 10(10) BPV-1 particles at each of two different sites on day 56. All calves were bled on days 3, 24, 55, 77, and 104 of the trial, and the sera were tested for reactivity with intact and disrupted BPV-1 particles by ELISA. At the time of challenge with BPV-1 virions (day 56), 19 of 20 vaccinated calves were seropositive for disrupted BPV-1 particles; sera from 3 of 20 calves reacted with intact BPV-1 virions. By day 77, 11 of 19 vaccinated calves had developed antibody titers to intact BPV-1 virions; only 1 calf in group 5 developed antibodies (transiently) against BPV-1 capsid epitopes. After challenge, 24 of 25 calves from the five groups developed intradermal fibromas, the biological end point of this study. Fibromas appeared to increase in size in group 5 (unvaccinated, inoculated controls), whereas most tumors from the four vaccinated groups (1-4) stabilized or decreased in size. Although the calves developed fibromas, 90% of calves (in groups 1-4) developed antibodies against disrupted BPV-1 capsid proteins whereas 58% developed antibodies that reacted with intact virions. The immunologic response of vaccinated calves to intact and disrupted BPV-1 particles appeared to be determined in large part by the various formulations of the vaccine, particularly the adjuvant.

Direct and maternal genetic effects due to the introduction of Bos taurus alleles into Brahman cattle in Florida: II. Preweaning growth traits.

Records of birth weight (BW), weaning weight (WW) and condition score (CS) from 1,467 Brahman and Brahman X Angus crossbred calves from Brahman and crossbred Brahman sires and Brahman, crossbred Brahman and Angus dams were collected at the Subtropical Agricultural Research Station, Brooksville, Florida, from 1971 to 1982. Best linear unbiased estimates (BLUE) of Brahman sire and dam group additive genetic effects (as deviations from Angus) and Brahman X Angus dam and calf group nonadditive (intralocus) genetic effects (as deviations from intralocus group genetic effects in the parental breeds) were obtained. Linear combinations of these were used to compute direct and maternal Brahman additive and Brahman X Angus nonadditive (intralocus) group genetic effects. The respective BLUE of these four effects were 5.99 +/- 2.08, -5.70 +/- 1.91, .52 +/- 1.81 and 2.85 +/- .72 kg for BW; 9.60 +/- 10.29, 8.76 +/- 9.47, 9.47 +/- 8.96 and 20.95 +/- 3.56 kg for WW; and -1.10 +/- .55, 1.64 +/- .50, 1.47 +/- .47 and .05 +/- .19 units for CS. Linear combinations of the BLUE of sire, dam and calf group genetic effects can be used to predict the genetic worth of crossbred groups composed of any combination of Brahman and Angus breeding. Nonadditive maternal group genetic effects were the most important factor for BW and WW, whereas nonadditive direct group genetic effects were the most important for CS.

Nitrogen metabolism and somatotropin secretion in beef heifers receiving abomasal arginine infusions.

Twelve Angus x Hereford heifer calves (233 kg) were fitted with abomasal infusion cannulas and used to study N and endocrine responses to abomasally infused arginine (Arg). Heifers were allotted randomly to three treatment groups and received continuous abomasal infusions (2 liters/d) of water (CON) or Arg solutions providing .33 g Arg.HCl/kg BW (LOW) or .50 g Arg.HCl/kg BW (HIGH) each day. A 12-d dietary adjustment period preceded a 7-d infusion and collection period. Each calf received 4,544 g DM/d of a basal diet in equal portions at 0600, 1200, 1800 and 2400. Calves were housed in individual metabolism crates and fitted with urinary bladder catheters for total excreta collection. On d 1 and 5, blood samples were collected at 15-min intervals for 8 h between 1200 and 2000. Single samples were obtained at 1400 on remaining days. The infusion of Arg increased the quantity of N retained by heifers (P less than .01) and the percentage of total N retained (P less than .10); however, no differences were observed between LOW and HIGH heifers. Increased (P less than .01) urinary N excretion by Arg heifers was associated with greater (P less than .05) quantities of urinary urea N and ammonia N. Blood urea N and serum Arg concentrations were highest (P less than .05) in Arg heifers, whereas total serum AA concentrations were lower (P less than .05) in Arg heifers than in CON heifers. Serum glucose and insulin concentrations were not affected (P greater than .10) by treatment. Characterization of somatotropin (STH) profiles revealed that amplitude and frequency of STH pulses were not affected (P greater than .10) by treatment, whereas mean (P less than .10) and basal (P less than .05) STH concentrations were elevated in HIGH compared to LOW heifers on d 1 and 5. The similar N retention responses of LOW and HIGH heifers and similar STH profiles of CON and LOW heifers suggest that the stimulatory effect of the HIGH dose on STH secretion occurred only after tissue N requirements had been satisfied.

Use of embryo transfer to produce twinning in beef cattle: Postweaning performance of Calves

Thirty-five purebred Angus calves, including six fraternal twin sets produced via embryo transfer, were fed during postweaning performance tests approximately 140 days in length. Singles had greater ( P < 0.01) on-test weights than twins, reflecting their heavier weaning weights. Postweaning gains of singles and twins were similar ( P=0.41). Twins were 13% lighter ( P=0.04) than singles at 365 days of age and had 3.5% smaller ( P=0.13) off-test hip heights. However, these differences were eliminated by adjustment for on-test weight. Off-test backfat thickness was not affected ( P=0.43) by type of rearing. Scrotal circumference of single and twin bull calves at the conclusion of the postweaning test did not differ ( P=0.58). Results indicate that calves raised as twins have acceptable postweaning performance.

Evidence for Genetic Control of Nematode Egg-Shedding Rates in Calves

Differences in nematode fecal egg counts from 167 purebred Angus calves born in 1986 and 133 born in 1987 that had been naturally exposed to infection on pasture were analyzed for sire effects. The calves were sired by 26 different bulls, all of which were related. Differences among fecal egg counts were attributable to sires (P less than 0.0002), to age of the calf (P less than 0.0007), to age of dam (P less than 0.05), and to collection year (P less than 0.0001). No variation in fecal egg count was attributable to calf sex (P greater than 0.23). After accounting for the effects of year, age of calf, and age of dam, heritability was estimated to be 29% (SE = 18%). It was concluded that a paternal contribution to the genome of each calf played an important role in determining average fecal egg output of the sire group. With heritability at 29%, selection against higher fecal egg counts or selection for lower fecal egg counts would be expected to produce measurable genetic change in a population.

心筋型白筋症に関する臨床ならびに臨床病理学的所見

Five Aberdeen Angus calves and one Hereford calf, 16 to 62 days of age, were studied. Of these six, two showed sudden death and four died within 5 days at the onset of therapy with injection of tocopherol, tocopherol and selenium, and cardiotonic. The calves showed clinical symptoms of tachycardia, tachypnea and cyanosis without stiff gait or recumbency. Serum enzyme activities (GOT, GPT, CPK, LDH) increased, and especially activity of LDH1 of LDH isoenzyme was high. Electrocardiogram of one calf showed sinus tachycardia and elevated ST wave. Pathologically, cardiac muscle of all calves affected the left ventricle and interventricular septum with the lesions of greyish white streaks. Histologic examination of the heart revealed severe degeneration of cardiac muscle cells, and skeletal muscle showed slight lesions, but one calf was not affected.All calves showed a marked decrease in serum tocopherol (66.1±43.7ug/dl in average) and selenium (10.2±6.0 ppb in average), and in tocopherol and selenium of organs. The contents of selenium in foodstuffs supplied in the farms were markedly low levels below 0.1 ppm D. M and a-tocopherol less than 3mg/100g D. M.It was considered that these calves were cardiac type of white muscle disease caused by deficiencies of tocopherol and selenium.

Brachygnathia superior and degenerative joint disease: a new lethal syndrome in Angus calves.

Brachygnathia superior and generalized diarthrodial degenerative joint disease were seen in 17 related, purebred Angus calves ranging in age from 2 days to 4 months. Craniometrical studies revealed decreased maxillary and palatine bone lengths and increased cranial, skull, and facial indices. Radiological evaluation of major appendicular joints demonstrated lipping of the joint margins with osteophyte formation, sclerosis of subchondral bone, and narrowing of joint spaces. Synovial fluid evaluation indicated joint degeneration but no etiologic agent. Rheumatoid factor analysis of plasma was negative. Grossly, all major appendicular joints were defective including the atlanto-occipital articulation. Lesions ranged from loss of surface luster to erosions and deep ulcers with eburnation of the subchondral bone and secondary proliferative synovitis. Histological changes were degeneration of the articular cartilage matrix, chondrocyte necrosis, flaking and fibrillation, chondrone formation, erosions and ulcers of the articular cartilage with subchondral bone sclerosis, vascular invasion with fibrosis, and chronic, nonsuppurative, proliferative synovitis. Growth plates had defective chondrocyte proliferation and hypertrophy with aberrant ossification of calcified cartilaginous matrix. Histochemical analysis of cartilage and bone failed to incriminate which component was defective, glycosaminoglycan or collagen, but indicated different distribution or absence of one or the other. Genealogic studies revealed a genetic basis for the new defect.

Inheritance and interaction of immune traits in beef calves.

Three sets of blood samples were obtained from beef calves of two experimental populations and assayed for various immunological measurements. The first set of samples was taken between 24 and 48 h after birth and quantified for IgG1 concentration. A second set was taken immediately prior to vaccination for infectious bovine rhinotracheitis virus (IBRV; at an average age of 164 d) and a third set taken 60 d post-vaccination. These later samples were quantified for antibodies specific to IBRV. Level of complement C3 was also quantified in the samples taken immediately prior to vaccination. Three hundred sixty-seven calves were from four Hereford lines; three lines were previously selected for growth traits and the fourth was a randomly selected control line. There were no consistent differences in immune traits among these lines. The second group of 165 animals were Angus, Hereford and Red Poll calves. While Angus calves had a higher mean IgG1 concentration at 24 to 48 h of age than Hereford or Red Poll calves, no differences among breeds were found for the other immune traits measured. Calves from older dams (>3 yr old) tended to have higher mean IgG1 concentrations, pre-vaccination IBRV antibody titers and complement C3 levels than calves from 2- and 3-yr-old cows. However, these calves had lower 60-d post-vaccination IBRV titers than calves from the younger cows (P<.05). As pre-vaccination IBRV antibody titer increased, post-vaccination IBRV antibody titer decreased (P<.05). All pooled heritability estimates did not differ significantly from 0 (range −.06 ± .08 to .21 ± .12), nor were there significant pheno-typic associations between the immune traits and growth performance.

The effect of the beef recipient female on embryo transplant offspring

Embryo transfer techniques were employed to investigate the importance of prenatal and postnatal maternal breed effects on calves of high growth potential (Chianina) and low growth potential (Angus). Six crossbred cow breed groups of known producing ability were used as recipients. These crossbred recipient females had been produced by artificia ly inseminating Angus and Hereford cows with semen from Chianina, Maine Anjou and Simmental bulls. Prior production records on the recipients cipients were used to calculate Most Probable Producing Ability (MPPA) estimates for each cow for birth weight and weaning weight. Donor breed differences were evaluated (P<0.01 to P<0.001) for all growth traits with Chianina calves having longer gestation lengths, heavier weights at all ages and greater hip heights than Angus calves. Chianina calves also were found to be more aggressive than Angus calves as determined by their higher scores (P<0.001) when entering the working chute and while restrained in the squeeze chute. Differences among the six crossbred recipient dam groups were not significant for any growth trait. From linear contrasts it was noted that Angus crossbred dams produced heavier calves at birth (P<0.005) and weaning (P<0.10) than Hereford crosses. When recipient females were grouped into quartiles based on MPPA estimates, no differences were detected among MPPA groups for either birth weight or weaning weight of their embryo transfer calves. Information to date from the present study suggests that the bovine recipient female has less influence on the performance of embryo transfer calves than would be anticipated based on earlier breed comparison studies. Apparently, if recipient cows from breeds that are reasonably similar in milking ability and mature size are used in an embryo transfer program, the maternal environmental differences are not great enough to prevent the transplant calves from expressing their growth potential. Crossnursing may also occur, so that transplant offspring with higher growth potentials may obtain enough milk from other dams to allow them to express their genetic potential. The potential milk producing ability of the beef recipient should still remain as a primary consideration by those involved in the transplantation of bovine embryos.

Cattle-Hypoderma lineatum Animal Systemic Insecticide Test, 1986

Abstract Government-owned Hereford, Angus, and Hereford-Angusiross calves and yearlings on pasture at Camp Stanley and Camp Bullis, Bexar Co., TX, naturally infested with the common cattle grub, Hypoderma lineatum Villers), are treated with new insecticides that were determined to be systemically active in the mouse-Cuterebra animal systemic insecticide test. Animals ire weighed and given insecticides in initial tests either orally by capsule (usually technical grade insecticide) or dermally by whole-body spray of 4 liters/ animal at &amp;gt; 1000 kPa [usually formulated as an EC in xylene (65 parts), Triton X-100 (10 parts), and AI (25 parts)]. In other tests, insecticides are administered dermally to cattle by pouron of a specific volume of insecticide (usually water-diluted EC as above or solution in oil) per body weight or intramuscularly or ubcutaneously by injection of a specific weight of insecticide per body weight. Normally cattle are treated with new insecticides initially at the highest lonlethal dosages as determined by cooperating veterinary toxicologists; maximum dosages of initial tests are 100 mg/kg orally and 1% spray. If initial dosages ire effective, cattle are given lower dosages in order to determine the minimum effective dosage. Other cattle are treated with titrated dosages of labeled systemics in order to determine systemic activity of label-listed dosages and less than label-listed dosages. After the treatment in May or Jun, the backs of treated cattle (usually 3-6 animals/treatment) and untreated cattle of the same age and breed from the same herd are examined monthly from Aug to Feb )f the next year for encapsulated cattle grubs. As cattle grubs appear, they are located on an outline map of the back of each animal; the cumulative number )f grubs in each animal is obtained. Effectiveness of a treatment is determined by comparing the average number of grubs in treated cattle with the average number in untreated cattle.

Osteopetrosis in cattle

Osteopetrosis, a generalized defect of the skeletal system has been reported in U.S. and Canadian Angus calves more recently in Hereford calves, a Simmental calf in Kansas, a Simmental calf in Holland, and a Dutch Friesian calf in Holland.&#x0D; The pathology and genetic data of osteopetrosis in Angus and Hereford calves are reported here.

Reciprocal crossbreeding of Angus and Hereford cattle 1. Growth of heifers and steers from birth to the yearling stage

Abstract Maternal (dam breed), direct (sire breed), and heterosis effects on growth were estimated from purebred Angus (A x A), purebred Hereford (H x H), and crossbred (H x A and A x H) steers and heifers bred at the Waikite Land Development block near Rotorua over a 4-year period. There were higher losses of calves from Hereford than Angus dams calving at 2 years-of-age, but no differences for older dams. Survival rate, both pre- and post-weaning, was higher for crossbred than purebred calves. Data from 934 calves alive at 5-month weaning and 897 calves alive at 13 months-of-age were analysed for liveweights and liveweight gains from birth to 13 months. Relative to Angus calves, Herefords were born 7 days later and were 3 kg heavier at birth, because of both maternal and direct effects. Both breeds had similar maternal effects on weaning and on subsequent weights. Post-weaning weights and weight gains for the direct effect favoured the Hereford. Comparison of purebred calves with the reciprocal crosses ...

Bovine embryo transfer pregnancies. I. Abortion rates and characteristics of calves.

Data were obtained from 1,908 pregnancies resulting from bovine embryo transfer procedures. Responses examined included sex ratio, fetal, neonatal and preweaning death losses, birth weight and calving assistance. The sex ratio for 1,751 embryo transfer calves examined was 51.11% males. Cows older than 10 yr that had become repeat breeders produced more (P less than .05) male calves than other donors. Breed of embryo, age and quality of embryos at the time of transfer, embryo storage time from collection to transfer, asynchrony of recipient with donor estrus and number of palpable corpora lutea in superovulated donors were not related to sex ratio (P greater than .05). The abortion rate between 2 and 3 mo of gestation in embryo transfer recipients was 3.15%, and between 3 to 7 mo, 2.14%. Neonatal and preweaning losses for 1,682 calves with complete information were 1) congenital defects, .54%; 2) death due to premature birth (7 to 8 mo of gestation), .18%; 3) dystocia-related deaths, 2.38%; 4) deaths of unknown causes at birth, 2.14%; 5) deaths of unknown causes from 24 h after birth to weaning, 1.43%; 6) deaths due to calfhood diseases, 1.25% and 7) deaths due to environmental factors, 1.13%. Total losses of 2-mo pregnancies due to abortion or death of calves or recipients were 14%. Birth weight of embryo transfer calves changed .29 kg/d of deviation from average gestation length (P less than .005) for pregnancies within breeds. Birth weight was also affected (P less than .005) by donor breed and recipient breed and age. Male calves averaged 2.19 kg heavier (P less than .005) than females. Calving assistance was affected by donor breed; Angus calves required the least assistance (P less than .005). Hereford, Holstein and Limousin calves were similar and intermediate; Simmental calves needed the most calving assistance. Recipient breed and age influenced calving ease, with younger recipients of Angus and Hereford descent requiring more assistance (average calving score, 2.1) than both cow (1.3) and heifer (1.5) recipients of the larger Continental European breeds. Characteristics of 305 non-embryo transfer calves were not significantly different from 185 embryo transfer calves from the same farms. We conclude that embryo transfer calves did not differ from the non-embryo transfer population in any of the characteristics studied.

The mechanical properties of immature osteopetrotic bone.

The elastic properties of the longer bones of the fore and hind limbs of an osteopetrotic Angus calf were measured using an ultrasonic technique. The same bones of a second Angus calf with unaffected bone tissue were also studied. The osteopetrotic bones were found to exhibit statistically significant lower values of density and mineral content than did the unaffected bones (P = .0054 and P = .0492, respectively). This result is contrary to what has been reported in the literature. The variations of the elastic properties and the density around the circumference of both the immature osteopetrotic femur and the unaffected femur were found to be similar to those previously measured on normal adult bovine femora.

Inheritance of maternal immunoglobulin G1 concentration by the bovine neonate.

Serum samples were collected between 24 and 48 h of age from 408 Herefored calves of a Selection Experiment and from 200 Angus, Hereford and Red Poll calves of another experimental population (Germ Plasm Utilization Project). Concentrations of immunoglobulin G1 (IgG1) were determined by single radial immunodiffusion. Breed or selection line of calf and age of dam were the most important factors influencing IgG1 concentrations (P less than .01). In the Germ Plasm Utilization (GPU) herd, Angus calves were highest, Red Polls were intermediate and Herefords were lowest in serum concentrations. Calves from Hereford lines selected for weaning weight, yearling weight or an index based on yearling weight and muscling score were lower in IgG1 concentration than calves from the randomly selected control line. In both populations immunoglobulin levels in the calf increased as age of dam increased. In Selection Experiment Herefords, increased calving difficulty was associated with a decrease in calf IgG1 levels (P less than .05). Heritabilities of calf serum IgG1 concentration, estimated from paternal half-sib analysis on a within line or breed basis, were .03 +/- .09 and .13 +/- .19 in the two populations. In the Selection Experiment Herefords, when the component of variance for selection line was added both to the numerator and denominator of heritability, the revised estimate was .09 +/- .09. Heritabilities of maternal effects on IgG1 concentration were also estimated (by nesting calves within maternal grandsires) on a within line or breed basis. These heritabilities were .23 +/- .17 and -.07 +/- .27 for the Selection Experiment and GPU populations, respectively. In the Selection Experiment population, when the variance component for selection line was added to the numerator and denominator of maternal effects heritability, the estimate was .27 +/- . .17. Those calves that died had a lower mean IgG1 concentration than the population average (P less than .01).

Pattern of milk intake as related to weaning traits of Angus calves grazing fescue-legume or fescue pastures

One hundred and ninety-seven lactation curves of mature Angus cows grazing fescue-legume or fescue pastures were described by a “gamma” model (average R 2 of 0.903, with no lack-of-fit detected). The curves were based on milk intake of Angus calves as determined by the weigh-suckle-weigh method. Milk intake curves of calves grazing fescue-legume pastures were similar at peak, but were more persistent than those of calves grazing fescue, reflecting a difference in forage quality ingested by their dams during the summer. Calves consuming larger amounts of milk as an average of lactation were heavier, taller and fatter at weaning. The relationship of milk intake and weaning traits was more pronounced for calves grazing fescue ( r = 0.46−0.76) than for those grazing fescue-legume ( r = 0.39−0.69). Calves that consumed larger amounts of milk had more even distributions of milk intake than calves consuming less milk as an average of lactation that consumed milk in this distribution grew more rapidly early, and subtion, the most desirable pattern of milk intake for calf growth was one described by a high peak and low persistency. Calves consuming similar amounts of milk as an average of lactation that consumed milk in this distribution grew more rapidly early, and subsequently consumed relatively large amounts of forage (if forage quality was high), and thus were heavier at weaning. The correlation between weaning weight and average milk intake through lactation would have been higher, except for the partial counterbalancing association between high average milk intake and relatively flat curves.

Influence of preweaning nutrition on growth of Angus calves provided a postweaning nutritional system resulting in discontinuous growth.

Postweaning growth patterns and preweaning milk and forage intake were observed over a 4-yr period for 137 Angus calves allowed either fescue-legume or fescue pastures preweaning. After weaning, calves grazed fescue pasture until spring for a slow growth phase and then fescue, orchard grass, bluegrass and ladino clover pastures for 4 mo. Following this period, the calves were confined and fed shelled corn and a 36% crude protein supplement until they reached 12 mm of fat over the 12th rib. The spring growing period and the finishing period were classified as a rapid growth phase. Calves that were fatter at weaning lost more fat, but gained more in wither height during the slow growth phase, than those that were thinner at weaning. Apparently, fatter calves were more capable of continuous skeletal growth on a low plane of nutrition because they could retrieve fat energy for this growth. In spring, calves that had been relatively fat at weaning held no advantage in fatness, but had larger frames. Therefore, during the rapid growth phase, they were able to fatten more rapidly than those that were thinner at weaning. Also, calves that were more efficient in preweaning growth had more capacity for rapid postweaning growth when restricted to relatively low quality pasture. Preweaning pasture type influenced pattern of postweaning growth. Part of this influence was associated with differences detected at weaning. An additional part was associated with efficiency of forage and milk utilization during the preweaning phase.