Cross Beef Research Articles

The effect of reducing feed intake following insemination on embryo survival in cattle

In farm animals early embryonic loss is recognised as a major cause of reproductive wastage. In sheep and pigs there is evidence that high energy intakes prior to ovulation and in early pregnancy depress systemic progesterone with a detrimental effect on embryo survival. The objective of this study was to investigate the effect of short term nutritional changes pre- and post-insemination on embryo survival and systemic progesterone in cattle. Preliminary results have been presented previously (Dunne etal., 1997).Oestrus was synchronised in 247 beef cross heifers aged 18-24 months using two injections of prostaglandin (PG) administered 10 days apart. At the oestrus following the first PG injection heifers were allocated to either a Low (L, 0.6 M) or High (H, 2.3M) pasture allowance for the 10 day period prior to artificial insemination (AI). AI was carried out at the oestrus following the second PG injection using semen from a single Limousin bull. On the day following AI, heifers were randomly reallocated to either a L or H pasture allowance until embryo recovery at day 14 to 16 or pregnancy diagnosis at Day 30.

Improving wholesale beef and pork product cross hedging

This study examines possible causes for the poor performance that has characterized the forward pricing and hedging practices used by participants in meat processing and merchandising operations. Alternative methods of managing price risk or meat merchandisers are presented and evaluated. The empirical analysis suggests pork and beef slaughter firms and merchandisers should seriously consider using more sophisticated cross hedge models to improve upon the poor performance of some forward contracting and hedging programs currently in use. © 1996 John Wiley & Sons, Inc.

Improving wholesale beef and pork product cross hedging

This study examines possible causes for the poor performance that has characterized the forward pricing and hedging practices used by participants in meat processing and merchandising operations. Alternative methods of managing price risk or meat merchandisers are presented and evaluated. The empirical analysis suggests pork and beef slaughter firms and merchandisers should seriously consider using more sophisticated cross hedge models to improve upon the poor performance of some forward contracting and hedging programs currently in use. © 1996 John Wiley & Sons, Inc.

Levels of bPSPB throughout single and twin pregnancies after AI or transfer of IVM/IVF cattle embryos

Blood plasma measurements of bovine pregnancy-specific protein B (bPSPB) during gestation in Alentejano beef cows were used to characterize twin pregnancies resulting from transfer of in vitro fertilized embryos (TWIN IVF; n = 25, beef crosses), single pregnancies resulting from transfer of similar embryos (SING IVF; n = 35, beef crosses) and single gestations resulting from artificial insemination (SING AI; n = 36, pure breed), as well as late embryonic mortality associated (HS; n = 10) or not associated (EM; n = 16) with heat stress. Blood samples were collected monthly starting at 40 days of pregnancy. Levels of bPSPB at 40 days were significantly lower in cows with EM (0.56 ± 0.18 ng ml −1) and HS (0.15 ± 0.09 ng ml −1) than in cows finally calving twins (3.63 ± 0.43 ng ml −1) or singletons (1.87 ± 0.14 ng ml −1) . In six out of ten cows of the HS group, levels of bPSPB rose above the detection limit only at 70 days after estrus, while in the EM group only 1 of 16 cows presented the same pattern ( P ⪕ 0.035). PSPB concentrations in TWIN IVF cows were significantly higher than those of SING IVF cows at 40 and 240 days of pregnancy (3.85 ± 0.30 vs. 2.04 ± 0.26 ng ml −1, and 715 ± 63 vs. 415 ± 58 ng ml −1, respectively; P < 0.001). The TWIN IVF group of cows presented significantly higher concentrations of bPSPB than SING AI cows at all stages of gestation, except at 180 days. In the single pregnancy groups, cows carrying fetuses originated by IVF embryos, when compared with cows carrying fetuses originated by AI, presented significantly higher concentrations of bPSPB from 100 to 210 days of pregnancy and at calving. The rate of increase in bPSPB from 40 to 240 days of gestation, taken from the slope of multiplicative regressions, was significantly higher in SING IVF than in TWIN IVF and SING AI groups of cows (3.284 ± 0.085 vs. 2.750 ± 0.101 and 2.852 ± 0.086, respectively; P < 0.0001). After spontaneous calvings, calves born from the SING IVF cows were significantly heavier than those born from either SING AI or TWIN IVF cows (58 ± 3 vs. 42 ± 2 and 39 ± 2 kg, respectively; P < 0.0001). Twin gestations were 8 days shorter than single ones ( P < 0.0001). In conclusion, bPSPB measurements at 40 and 70 days of gestation are useful to diagnose embryo losses occurring later then 21 days of gestation. Heat-stressed cows with embryo losses presented a retarded pattern of bPSPB production, suggesting an impaired metabolic function of the trophoblast until near 70 days of gestation. Significantly higher amounts of bPSPB are produced at 40 days in twin pregnancies. A larger variation and higher bPSPB production were observed in cows carrying crossbred fetuses derived from IVF techniques than in purebred AI'ed cows. These results suggest that there is a relationship between fetal growth rate and PSPB increase during pregnancy in cattle.

An economic comparison of beef cattle genotypes for feedlot traits at their optimal slaughter end point

A bioeconomic model is used to compare beef breeds and crosses for their economic performance in the feedlot. Breeding objectives for each breed and cross are also calculated. Comparisons are made on the basis of the expected purchase-price premium paid for a breed, cross or animal when slaughtered at its profit-maximizing end point. These comparisons are relevant to commercial beef producers who ultimately have to choose between genotypes. Purebred Charolais are expected to capture a premium over purebred Angus of approximately $71 and $45 animar−1 for steers and heifers, respectively. Simmental, Limousin and Hereford purebreds are intermediate, with differences between them relatively small in comparison with the expected effects of errors in model parameters. Crosses between exotic type (Charolais, Simmental and Limousin) and British type (Hereford and Angus) breeds have larger increases in purchase-price premiums over the mid-parent mean than crosses within the types. Averaged economic weights for 1% changes in the mean of +12 g d−1, −80 g d−1 and 0.6% in daily gain, daily feed intake and dressing percentage are $3.7 animal−1, $1.8 animal−1 and $8.4 animal−1, respectively. These are relatively consistent across breeds, crosses and sexes. In contrast, economic weights for fat depth at a constant weight are shown to be nonlinear and therefore are highly dependent on the breed, cross and sex and the slaughter end point at which they are calculated. At the economic optimum slaughter point in the base, exotic breeds and crosses between them tended to have negative economic weights for a reduction in fat depth, whereas British breeds were the opposite. Economic weights tend to be small and positive for a reduction in fat depth in crosses between the two breed types. Key words: Beef cattle, feedlot, end point, optimization, bioeconomic model

Eating quality of beef from different breeds

1.Major changes have taken place in the beef industry over recent years - in particular, the introduction of several continental breeds which have the potential for producing larger and leaner carcases. The Canadian Holstein has also been used extensively in the dairy industry, replacing British Friesians, with the result that beef cross carcasses from the dairy herd have tended to be larger and have poorer conformation.2.As a consequence of these changes there is concern in the industry that beef of poorer eating quality is now being produced. For this reason, and to aid in the development of MLC's Blueprint for beef eating quality, this trial was set up in collaboration with Genus to evaluate the eating quality of two traditional British beef breeds and four continental breeds slaughtered at different fatness levels. 3.All progeny included in the trial were from Holstein Friesian type dams. They were sired by the following breeds:- Limousin (LM), Charolais (CH), Belgian Blue (BB), Piemontese (PM), Aberdeen Angus (AA) or Hereford (HF) and were finished on an 18 month beef production system.

Factors affecting subcutaneous fat depth at two sites on beef carcasses

Over a 12-month period, fat depths at the P8 rump and 12-13th rib sites were measured on 10968 beef carcasses at 4 Tasmanian abattoirs. All cattle were assigned to 1 of 5 breed types: British beef, dairy, dairy-beef cross, beef cross, and European and European cross. Dairy-beef cross and European breeds were excluded from the analysis because of small numbers. Sex and age (dentition) were recorded. As the data set was unbalanced and no single relationship between P8 rump and 12-13th rib sites applied, models describing the relationship between fat depths at the 2 sites were developed for subsets of the data. These showed that breed type, sex, age, season, and carcass weight all affected the relationship between fat depths at the 2 sites. In general, British beef and beef cross cattle could be considered as 1 group, but dairy cattle were different. In the former group, for the no-teeth age class a seasonal and sex effect was evident, giving rise to 4 models, 1 for each of the steer and heifer groups in winter-spring and summer-autumn. For the no-teeth dairy cattle there was no sex effect and all seasons were pooled to form an overall model. For older cattle (2, 4, and 8 teeth) there was significant monthly variation, and few overall models could be developed. In addition, the relationship between fat depths at the 2 sites was generally independent of carcass weight in older cattle. The analysis revealed that within the subcutaneous fat depot the relationship between sites for fat depth can be influenced by a range of variables.

Effect of Calf Management on Carcass Characteristics and Palatability Traits of Veal Calves

Objectives were to explore the feasibility of producing grain-fed veal. Fifteen Holstein bull calves and two Holstein beef cross females were fed milk only or were weaned by 28 d and fed concentrate. Milk-fed calves were reared in painted, metal-sided pens (1.2m × 1.8m) on rubber covered concrete (hosed daily); grain-fed calves were in outdoor movable pens (1.2 × 2.5m). Mean slaughter age was 127 d for both groups. Average birth weight, final BW, and average daily gains were 98, 98, and 97% as much for grain-fed as for milkfed calves. Total 127-d consumption was 1488kg of milk per milk-fed calf, with peak 14-d consumption of 19.9 kg/d, and consumption for grain-fed calves was 103kg of milk and 351kg of concentrate. Blood hemoglobin (10.75 g/dl) did not differ. All calves finished the experiment; scour incidence and medications (48 vs. 0) were much higher with milk feeding. Growth rate (d 28 to 127) was 1.1 kg/d for grain feeding compared with 1.0 kg/d (less than expected) for milk feeding. Hide was not removed until 24h when carcasses were evaluated for USDA grade factors. Milk feeding resulted in lower lean and overall maturity scores; lighter color; more flank fat streaking; greater fat thickness; more kidney, pelvic, and heart fat; lower Warner-Bratzler shear values of loin chops; and higher percentage graded as veal. Composition of longissimus muscle, cooking characteristics, and sensory panel attributes did not differ. Lean maturity and color were not related to shear values or sensory panel evaluations. Total pigment content was correlated positively with flavor intensity.

The effect of haulage distance oh the performance and welfare of beef bulls and the eating quality of beef

Previous studies in this area have tended to concentrate on the effects of short haulage distances on the behavioural patterns of bulls (Kenny and Tarrant, 1987) and the incidence of dark cutting beef following pre slaughter mixing (Price and Tennessen, 1981). To date, the current authors are unaware of any study which has been conducted to evaluate the effects of haulage distance and sex on the welfare of beef cattle and the eating quality of beef. As part of a much larger recording scheme such a study was conducted with 96 young continental cross beef bulls and 8 continental cross beef steers.50 beef bulls and 8 beef steers from similar farms were subjected to a road journey of some 250 miles lasting about 480 minutes to an abattoir near Aberdeen. A further 46 beef bulls, which had originally come from similar farms to those outlined above, were subjected to an average road journey of 10 miles to the same abattoir, this journey lasting approximately 20 minutes.

Mastitis in beef cows and its effects on calf weight gain

Quarter milk samples from 51 purebred (Angus, Polled Hereford, and Simmental) and 69 crossbred (Angus x Simmental x Charolais three-way cross) beef cows were collected aseptically at three times during lactation to determine the prevalence of intramammary infection, milk somatic cell counts (SCC), and effects of infection on calf weight gain. Quarter infection prevalence was 13.1, 14.9, and 27.5% in early, mid, and late lactation; corresponding cow infection prevalence was 25.8, 29.2, and 54.4%. Staphylococcus aureus was isolated from 2.9, 2.7, and 3.2% of quarters in early, mid, and late lactation, respectively. Corynebacterium bovis, generally regarded as a minor pathogen, was isolated from 4.0, 7.6, and 18.2% of quarters at the three respective times. Geometric SCC means (10(3) cells/ml) were 1,522, 344, and 509 for S. aureus-infected quarters; 344, 899, and 221 for Staphylococcus hyicus-infected quarters; 65, 36, and 86 for C. bovis-infected quarters; and 20, 17, and 18 for uninfected quarters in early, mid, and late lactation, respectively. Adjusted 205-d weight gain for calves with S. aureus-infected dams was 9.6 kg less (P less than .05) than for calves with uninfected dams. Adjusted 205-d weight gain for calves with dams infected with any mastitis pathogen did not differ significantly from that of calves with uninfected dams. At weaning half of the infected cows and half of the uninfected cows were given an intramammary infusion product containing 300 mg of cephapirin benzathine in each quarter; the remaining cows were untreated controls. Quarter samples were collected aseptically from all cows 14 to 28 d after subsequent calving. Quarter prevalence of infection after calving was lower (P less than .05) in treated (8.2%) than in control (22.4%) cows. Significantly more infections present at weaning were eliminated in treated than in control cows, but the new infection rate during the dry period and early lactation did not differ between the two groups.

Oestrous and reproductive performance of early- and late-calving beef cows

Abstract The relationship between calving date of cows in spring and their subsequent reproductive and calf performance was studied in two calving years. Cows (4 years or older) with their calves were drafted into two grazing groups as they calved in September and early October, an ‘Early group’ and a ‘Late group’ differing in average calving date by 19.3 days (maximal range within group = 22 days). The cows represented 95 animals of dairy-cross breeds and 213 of beef breeds or crosses. All breed groups were represented in both calving groups, with 161 cows in the Early group and 147 in the Late group. Between-group differences in cow weights were small pre-calving (3 kg, NS) and similarly at weaning (-1 kg, NS). However, the Early group was 33 kg lighter in November than the Late group at a fixed time interval after calving. Birth weights were 2.1 kg (6.2%) less for Early-born than Late-born cal ves. Weaning weights, unadjusted for birth date, were 15 kg (9.0%) greater for calves out of Earlythan Late-group cows. Significantly higher proportions of cows in the Early than Late group were detected in oestrus by the start of mating (respectively 0.61 v. 0040), corresponding to a delay of about 10 days in oestrous date, about half of the delay in previous calving date. The difference in oestrus was not translated to a significant advantage in pregnancy rate in an 8-week mating period (0.93 for the Early group and 0.89 fortheLategroup). The corresponding calving dates 1 year later differed between groups by only 1.8 ± 2.1 days. There were no interactions of year with calving group. The overall apparent 5% advantage to the Early group in future herd output (calf numbers and weights) mainly resulted from the non-significant difference in pregnancy rate.

GENOTYPE-NUTRITION INTERACTION FOR REPRODUCTION OF BEEF COWS

Two levels of feed during early lactation (70 and 100% of NRC requirements) were used for five groups of genotypes (Herefords, small beef breed crosses, large beef breed crosses, small beef by dairy crosses and large beef by dairy crosses). Days to first ovulation (DFO), days to pregnancy (DP) and pregnancy rates were measured over 2 yr. No interaction of feed level by breed group was found for any measure of reproductive performance, milk yield or weaning weight of calf. The lower level of feeding significantly decreased DFO (by 6 d) and DP (by 5 d). Dairy crosses had similar DFO to Hereford, but less than beef crosses. When milk yield and weight were used as covariates, replacing breed group classifications, DFO was found not to be significantly influenced by 6-wk measurements of milk (P = 0.11) nor weight (P = 0.89). Number of days to pregnancy was similarly unaffected by milk yield (P = 0.19), although it was increased by increased weight of cow (P = 0.03). Significant (P &lt; 0.05) differences among breed groups remained after adjustment for weight and milk for DP but not for DFO. More variation was accounted for in DFO (R2 = 0.48) than DP (R2 = 0.20). Repeatability of performance from one year to the next was higher for DFO (0.26 ± 0.13) than for DP (0.00 ± 0.15). Key words: Genotype-nutrition interaction, beef cows, reproduction

The effect of milk substitute input on the lifetime performance of calves reared for beef production

A randomised block experiment, involving 126 British Friesian and Friesian cross beef male calves which were initially 46.7 kg and 10 days old, has been carried out to examine the effects of the quantity of milk substitute consumed per calf on the lifetime performance of calves reared for beef production. The three treatments were (1) 400 g milk powder per head daily, weaned at 6 weeks old (2) ad libitum intake of milk powder, weaned at 6 weeks (3) ad libitum intake of milk powder, weaned at 8.5 weeks. Calves on treatment 1 were bucket fed twice daily, while those on treatments 2 and 3 suckled the milk from teats. The calves were purchased in three groups in (1) October, 1983 (2) December, 1983 and (3) February, 1984. Three commercial brands of acidified milk substitute were used, one for each group. All animals were individually penned until after weaning. They were offered a pelleted concentrate, based on barley and soyabean meal, ad libitum from two weeks old until intake reached a maximum of 2.7 kg per head daily. Hay was offered ad libitum to six weeks of age and well preserved grass silage was offered ad libitum thereafter. Group 1 calves were on an 18 month grass/cereal beef system, group 2 on a 22 month grass system and group 3 on a 15 month silage/ cereal system. The chemical compositions of the milk substitutes, concentrate and silage are given in Table 1.

Comparison of Two- and Three-Way Rotational Crossing, Beef × Beef and Beef × Brown Swiss Composite Breed Production

Data collected at the Fort Keogh Livestock Research Laboratory on 912 male calves (M) and 954 heifer calves (F) in years 1967 through 1977 were used to estimate the amount of heterosis in two-way (2W) and three-way (3W) rotational crossing systems and advantages of a beef × beef composite (BC) resulting from crossing straightbreds (SB), Hereford (H), Angus (A) and Charolais (C). In conjunction with the main study, 161 male calves and 191 heifer calves produced from matings of crossbred beef × Brown Swiss sires and dams were used to compare performance of a beef × dairy composite (BSC) with the other rotational crossing and beef composite groups. All calves were raised on native range and were weaned at an average age of 193 d. Percent increases over SB shown by 2W, 3W and BC calves combined over three generations were: 3.3, 3.6 and 5.2, respectively, for birth weight; 4.4, 6.6 and 6.7 for 205-d weaning weight; 4.8, 7.3 and 7.1 for average daily gain birth to weaning; 2.0, 2.9 and 2.6 for weaning score. These estimated increases over SB were all highly significant. For gain from birth to weaning and 205-d weight, 3W was superior (P<.01) to 2W. For all growth traits, BC exceeded (P<.01) 2W but the performances of BC and 3W were similar. The weaning scores for 2W, 3W and BC calves were similar and were only 2.5 percentage points higher than scores from SB calves. The heterosis levels in each system were maintained from the first to the third generation. As sire breeds in 2W and 3W rotations, H and C consistently exceeded (P<.05 to P<.01) A for most growth traits. In 2W, the AC and HC backcross dams produced calves with heavier (P<.01) birth and weaning weight than AH backcross dams. The BSC calves were heavier (P<.01) at birth and gained faster from birth to weaning than those of 2W and 3W rotations and BC, but weaning scores of BSC calves were 3.0 percentage points lower (P<.01) than the beef crosses.

Methods of improving the utilization of cereal straw by ruminants. V. The effect of molasses and dried grass

Sixteen castrated beef crosses (290 ± 7.8 kg) were used in a 4 × 4 factorial design. Straw treated with urea alone or urea plus 4, 8 or 12 kg of molasses/100 kg straw was offered to the steers ad libitum. The straw was supplemented with 5, 10, 15 or 20 g grass DM/day/kg metabolic liveweight. Straw intake (g DM/day/kg metabolic liveweight) was 57, 58, 62 and 55 for the four levels of grass, and 56, 59, 61 and 57 for the four levels of molasses, respectively. There was no interaction between grass and molasses. The liveweight change of steers increased with increasing grass. Molasses had no definite effect on liveweight change.

PATTERNS OF MUSCLE, BONE, AND FAT ACCRETION IN THREE BIOLOGICAL TYPES OF FEEDLOT BULLS FED THREE DIETARY ENERGY LEVELS

The effect of three types of diet on the carcass composition of 71 feedlot bulls of three biological types (Dairy Cross (DX), Hereford Cross (HX), and Beef Cross (BX)) was studied over a 2-yr period. Diets consisted of pelleted alfalfa with 0, 35 or 85% grain. Serial slaughter and carcass dissection into eight wholesale cuts and component tissues were carried out over an age range of 392–636 days. Interactions of biological type with diet-year were generally not significant for actual weight of muscle, bone and fat, or for weight of these tissues at a constant side subcutaneous fat weight of 16 kg. There were few significant effects of biological type or diet-year on the ratio of actual weight of subcutaneous to intermusclar plus body cavity fat. HX bulls had significantly less muscle and less bone than BX or DX, based on actual weights, but the rate of tissue accretion relative to side subcutaneous fat was the same for the three biological types. Animals on the lowest level of dietary energy had less weight of fat than did those on an 85% grain diet, but diet-year growth coefficients of tissue weights relative to side subcutaneous fat weight were generally homogeneous. It was concluded that effects of dietary energy were consistent over the biological types studied and for most of the wholesale cuts. Key words: Feedlot bulls, diet, biological types, tissue growth

BOOK REVIEWS

Book reviewed in this article: John McFadyean, Founder of Modern Veterinary Research. Iain Pattison. J. A. Allen. Proceedings of XII Seminar, Sheep and Beef Cattle Society of the New Zealand Veterinary Association. Pictorial Anatomy of the Cat. S. G. Ginbert. Grazing Animals. Editor F. H. W. Morley. Equine Medicine and Surgery. Editors R. A. Mansman and E. S. McAllister. Applied Veterinary Anatomy. R. E. Habel. Beef Production from Different Dairy Breeds and Dairy Beef Crosses. Editors C. J. More and O'Per rail. Animal Health. David Sainsbury.

A comparison of preruminant bull calves of the Hereford × Friesian, Aberdeen Angus × Friesian and Friesian breeds

ABSTRACTTwenty-four bull calves, eight Hereford × Friesian, eight Aberdeen Angus × Friesian and eight Friesian, were reared from birth to slaughter at 13 weeks of age solely on a milk substitute diet given ad libitum.Samples of jugular blood were taken at weekly intervals from 5 days to 89 days of age for determination of concentrations of prolactin, growth hormone (GH), insulin and total thyroxine (T4) in plasma, tri-iodothyronine (T3) uptake, and thus free T4 index (FTI).The Friesian calves had a higher mean body temperature and lower mean T3 uptake than did either of the beef crosses.The Aberdeen Angus cross had a higher mean dry-matter intake per unit of metabolic body size (DMI/W0·73), heart rate and plasma insulin concentration than did the Hereford cross, and a higher insulin concentration but not a higher heart rate than did the Friesian. Live-weight gain and DMI/W0·73 for the Friesian was intermediate between that of the Aberdeen Augus cross and the Hereford cross.DMI/W0·73 was positively correlated with insulin: GH ratio, prolactin: GH ratio and T4: GH ratio.The increase in heart rate per unit DMI/W073, a measure of the heat increment of feeding, was negatively correlated with the plasma insulin concentration, insulin: T4 and insulin: GH ratios.Prolactin concentration, GH concentration and T3 uptake declined with age, whereas insulin concentration, T4 concentration and FTI increased with age. The relationship was linear for prolactin and insulin concentrations, but curvilinear for the other variables. The Friesian breed had a higher GH concentration than did the beef crosses during the first 12 days of life. The large increase in insulin concentration for the Aberdeen Angus × Friesian occurred from about 47 days of age. The peak T4 concentration and the lowest T3 uptake of the breeds occurred between 33 and 42 days of age.Possible mechanisms for the control of dry-matter intake by preruminant calves and the difficulties associated with prediction of performance from plasma metabolic hormone concentrations obtained at a young age are discussed.

Onset of puberty in heifers of diverse beef breeds and crosses.

Puberty traits of straightbred and crossbred heifers (n = 301) were evaluated under pasture conditions. Breed groups represented were straightbred Hereford and Red Poll, reciprocal crosses of these two breeds, Angus X Hereford, Angus X Charolais-Cross, Brahman X Hereford and Brahman X Angus. Breed group was an important (P less than .01) source of variation in heifer weights and in age at puberty. Straight-bred Red Poll and Red Poll cross heifers were youngest at puberty, Angus X Hereford and Angus X Charolais-Cross were intermediate, and straightbred Hereford and Brahman crosses were oldest at the onset of puberty. At the beginning of their first mating season at 19.5 mo of age, 96% of the straightbred Red Polls, 95% of Red Poll crosses, 81% of Angus X Herefords, 89% of Angus X Charolais-Crosses, 68% of straightbred Herefords, 48% of Brahman X Herefords and 74% of the Brahman X Angus had attained puberty. Results of a diallel analysis of Hereford-Red Pool matings indicated that maternal influence of the Red Poll breed was superior (P less than .01) to Herefords for body weight up to 24 mo of age and incidence of puberty at 11.5 mo. Red Polls also exceeded Herefords in direct effects for puberty percentage at 11.5, 15 and 19.5 mo of age. Heterosis was significant for puberty percentage and weight. Breed group differences in pregnancy rate at 24 mo were not significantly.

Growth and Compositional Characteristics of Young Bulls in Diverse Beef Breeds and Crosses

Growth and Compositional Characteristics of Young Bulls in Diverse Beef Breeds and Crosses