Reproductive efficiency of F1 and reciprocal backcross beef cows under contrasting environments

1991 ◽  
Vol 71 (4) ◽  
pp. 969-985 ◽  
Author(s):  
G. W. Rahnefeld ◽  
R. M. McKay ◽  
G. M. Weiss ◽  
H. T. Fredeen ◽  
J. A. Newman ◽  
...  
Keyword(s):  
Beef Cattle ◽  
Key Words ◽  
Beef Cows ◽  
Performance Criteria ◽  
Reproductive Efficiency ◽  
Mating Opportunities ◽  
The Difference ◽  
Reciprocal Backcross

A population of 860 F1 and reciprocal backcross females representing Hereford (H), Angus (A), Shorthorn (N), Charolais (C) and Simmental (S) breeding were evaluated for reproductive efficiency under two contrasting environments (Brandon, Manitoba and Manyberries, Alberta). The F1 included the HA, CN and SN and the reciprocal back-crosses were HCH, CCH, ACA, CCA, HSH, SSH, ASA, SSA, NSN, SSN, NCN and CCN. All females were bred to Limousin bulls. The data collected from 1980 to 1986 comprised 3108 mating opportunities and 2523 pregnancies. For dam crosses common to both locations (HA, SN and specific dam crosses involving S) differences in performance criteria occurred with females at Manyberries recording greater cow losses, higher conception and weaning rates, and more weight of calf weaned than at Brandon. Combining these performance elements gave the females at Manyberries an advantage for weight of calf weaned per mating opportunity (162 ± 3.2 vs. 152 ± 3.0 kg). Barren culls comprised the largest proportion of cow losses at both locations with HA and NSN greatest and ASA lowest at Brandon, and SSH greatest and SN lowest at Manyberries, all significant at P ≤ 0.05. None of the differences for C cross females was significant (P > 0.05). Weaning rates per mating opportunity for dam crosses common to both locations indicated the ASA highest and the SSH lowest at both locations, the difference being 22.9% at Brandon and 13.2% at Manyberries. For the HA, CN and C backcross comparisons, the highest weaning rate per mating opportunity was recorded for the HA (73.3%) and the lowest for the CCA dam cross (62.4%). At both locations, the SN dams produced the most weight of calf weaned per mating opportunity with the lowest values recorded by the HA and NSN dam cross at Brandon and the HSH dam cross at Manyberries with the CN dam cross recording the highest values and the CCA and ACA the lowest. For all performance criteria calves out of F1 dams had an advantage over calves from backcross dams. Key words: Beef cattle, cow productivity, crossbreeding

scholarly journals LIFETIME REPRODUCTIVE EFFICIENCY OF FIRST-CROSS BEEF COWS UNDER CONTRASTING ENVIRONMENTS

1981 ◽  
Vol 61 (3) ◽  
pp. 539-554 ◽  
Author(s):  
H. T. FREDEEN ◽  
G. M. WEISS ◽  
J. A. NEWMAN ◽  
J. E. LAWSON ◽  
G. W. RAHNEFELD
Keyword(s):  
Environmental Stress ◽  
Data Base ◽  
Reproductive Performance ◽  
Beef Cows ◽  
Performance Criteria ◽  
Reproductive Efficiency ◽  
Pasture Management ◽  
Mating Opportunities ◽  
Sire Breed ◽  
Slight Advantage

A population of 1150 first-cross females representing the Hereford-Angus (control) and nine crosses produced by mating bulls of the Charolais (C), Simmental (S), and Limousin (L) breeds with cows of Hereford (H), Angus (A) and Shorthorn (N) breeding provided the data base for breed-cross comparisons of lifetime reproductive performance under two contrasting environments. These data comprised 6022 mating opportunities and 5053 pregnancies recorded during a period that commenced with the breeding season of 1971 and terminated at weaning in the fall of 1979.There were substantial location differences in all performance criteria with the relatively stringent range environment (Manyberries, Alberta) resulting in greater cow losses, lower conception and weaning rates, and less weight of calf weaned than occurred under semi-intensive pasture management (Brandon, Manitoba). Barren culls comprised the largest proportion of cow losses with sire breed ranking C < S < L and dam breed ranking A < H < N for the exotic crosses at both locations. The C cross also ranked lowest for total attrition and highest for percentage conception and percentage of calves weaned per mating opportunity at each location. At Manyberries, these elements of performance combined to give C cross dams a slight advantage in weight of calf weaned per mating opportunity (143 vs. 139 kg for S cross dams), but this ranking was reversed at Brandon (176 vs. 181 kg for S cross). First-cross dams out of A cows at Manyberries ranked above the N cross in weight of calf weaned (139 vs. 135 kg), but this position was reversed at Brandon (172 vs. 176 kg). These changes in ranking at the two locations (C vs. S and A vs. N) may have reflected differences in the degree of environmental stress imposed by the lactation process. All of the sire breed (C, S, L) and dam breed (H, A, N) combinations ranked above the HA control for weight of calf weaned per mating opportunity. However, for this measure of productivity the L vs. HA difference at Manyberries (125 vs. 124 kg) was negligible.

scholarly journals Reproduction performance of beef cattle mated naturally following synchronization in the Central Bushveld bioregion of South Africa

2015 ◽  
Vol 44 (5) ◽  
pp. 70-74
Author(s):  
SM Grobler ◽  
MM Scholtz ◽  
JPC Greyling ◽  
FWC Neser
Keyword(s):  
South Africa ◽  
Beef Cattle ◽  
Breeding Season ◽  
Recovery Period ◽  
Beef Cows ◽  
First Year ◽  
Natural Mating ◽  
The Difference ◽  
Calving Season ◽  
Main Component

The estimated calving percentage of beef cattle is 62% in the commercial sector of South Africa. Fertility is regarded as the main component influencing total herd efficiency in beef cattle. If the long calving seasons can be shortened and the calving percentage increased, more and heavier calves with a more uniform age can be weaned. Cows calving earlier in the season also have an extended “recovery period” and have the opportunity to calve in a better body condition during the next season, compared to cows calving late in the season. Cows that calve early also have a better chance of conceiving in the next breeding season and are generally seen as the more fertile animals. Research has been undertaken to evaluate the effect of oestrous synchronization followed by natural mating on the calving rate and calving distribution of multiparous beef cows. In this trial Bonsmara cows were mated naturally after synchronization over a period of four years (2009 - 2012) in an extensive production system on natural sour-mixed bushveld. The synchronized cows calved earlier during the 2009 calving season and cows in anoestrus started cycling again. The average days-to-calving after the start of the breeding season was 243 days for the synchronized cows and 267 for the non-synchronized cows. The calves born from the synchronized cows were therefore, on average, 24 days older than the calves born from the non-synchronized cows. From 2010 onwards the difference declined and it seems the biggest effect was obtained during the first year of synchronization.Keywords: Beef cattle, Marikana thorn veld, natural mating, oestrous synchronization

scholarly journals The effects of gonadotrophin releasing hormone in prostaglandin F2α-based timed insemination programs for beef cattle

2001 ◽  
Vol 81 (3) ◽  
pp. 335-343 ◽  
Author(s):  
J. A. Small ◽  
J. D. Ambrose ◽  
W. P. McCaughey ◽  
D. R. Ward ◽  
W. D. Sutherland ◽  
...  
Keyword(s):  
Beef Cattle ◽  
Key Words ◽  
Prostaglandin F2α ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Progesterone Concentration ◽  
Gender Ratio ◽  
Plasma Progesterone ◽  
Estrous Synchronization ◽  
Gonadotrophin Releasing Hormone

Trials were conducted in the spring (May; n = 324) and fall (October; n = 132) with crossbred continental-type beef cows assigned on the basis of parity and postpartum interval to one of three timed-AI treatments and one of two post-AI treatments. The timed-AI treatments were: (DPG) double (14 d apart) PGF2α (Lutalyse®) and AI (day = 0) 72 h after the second PGF2α (day –3); (OVS) Ovsynch® with the second GnRH (Factrel®) at 48 h and AI at 66 h; and (BRC) the same as OVS except that the second GnRH was given at the time of AI. Half of the cows within each treatment were given GnRH on day 14. Plasma progesterone concentrations were determined for the day of the first injection and on days –3, 0, 14, and 21. Timed-AI pregnancy was diagnosed by ultrasonography at day 42 and confirmed at calving. For DPG, OVS and BRC, PGF2α responder rates were 75.9, 51.4 and 71.3%, respectively, in spring (P < 0.05) and 70.4, 70.4 and 59.1% in fall (P > 0.05), and AI pregnancy rates were 28.7, 44.9 and 44.4% in spring (P< 0.05) and 25.0, 40.9 and 43.2% in fall (P > 0.05). Post-AI GnRH had no significant effect on pregnancy or conception rates or day 21 progesterone. The use of GnRH in the PGF2α based timed-AI program improved pregnancy rates and the BRC treatment was as effective as OVS. Neither postpartum interval nor initial progesterone concentration influenced (P >0.05) the effect of GnRH on AI pregnancy rate, and GnRH had no effect (P > 0.05) on twinning rate or gender ratio. Key words: Beef cows, estrous synchronization, pregnancy, timed-AI, progesterone

Machine effects on accuracy of ultrasonic prediction of backfat and ribeye area in beef bulls, steers and heifers

2000 ◽  
Vol 80 (1) ◽  
pp. 19-24 ◽  
Author(s):  
P. K. Charagu ◽  
D. H. Crews Jr. ◽  
R. A. Kemp ◽  
P. B. Mwansa
Keyword(s):  
Beef Cattle ◽  
Key Words ◽  
Standard Error ◽  
Important Relationship ◽  
Ribeye Area ◽  
Beef Bulls ◽  
The Difference

Pre-slaughter ultrasound and carcass measurements of ribeye area (REA) and backfat (FAT) were recorded on composite beef bulls (n = 60), heifers (n = 60) and steers (n = 60). Breed composition of the composite was: 0.44 British (Hereford, Angus and Shorthorn) 0.25 Charolais, 0.25 Simmental and 0.06 Limousin. The Aloka SSD-1100 (AL) and the Tokyo Keiki CS 3000 (TK) ultrasound machines were compared by evaluating the difference between ultrasound and carcass measurements (bias), and the standard error of prediction (SEP). AL under-predicted REA in all three sexes while TK overpredicted heifers and steers and underpredicted bulls. Both machines were similar in accuracy among bulls for REA. For FAT AL underpredicted all three sexes while TK underpredicted heifers and had very small bias for bulls and steers. SEP for FAT were similar for both machines. Both machines underpredicted REA in larger muscled cattle and overpredicted in smaller-muscled cattle. Both machines also underpredicted FAT in fatter animals and overpredicted FAT in leaner animals. Machines were similar in accuracy among cattle with larger REA but differed significantly (P < 0.05) among smaller-muscled cattle. Machines were comparable in accuracy among animals of all FAT sizes. This study demonstrates that there is an important relationship between machine and the size and depth of muscle and backfat, respectively, and consequently between machine and sex, in accuracy of ultrasound prediction. Key words: Beef cattle, ultrasound, accuracy, back fat, ribeye area

Genetic trends for weaning weight during development of a multibreed population of beef cattle in two contrasting environments

2000 ◽  
Vol 80 (1) ◽  
pp. 191-193
Author(s):  
J. J. Tosh ◽  
R. A. Kemp
Keyword(s):  
Natural Selection ◽  
Beef Cattle ◽  
Key Words ◽  
Genetic Component ◽  
Weaning Weight ◽  
Common Base ◽  
The Difference ◽  
Selection Differentials ◽  
Genetic Trends

Genetic trends for weaning weight were determined in two herds of multibreed beef cattle that originated from a common base and were subject to mutual breeding policies in separate environments. The herds diverged for the direct though not the maternal genetic component of weaning weight within the 13-yr period examined; in the final year, the difference (P < 0.001) between the herds was almost 3 kg. This could have been partly due to unequal selection differentials and generation intervals. Results suggested the extent of natural selection also differed between the two environments. Key words: Beef cattle, crossbreeding, genetic trends, selection, weaning weight

Slaughter and carcass traits of calves from first-cross and reciprocal back-cross beef cows

1994 ◽  
Vol 74 (4) ◽  
pp. 621-632 ◽  
Author(s):  
J. A. Newman ◽  
A. K. W. Tong ◽  
S. D. M. Jones ◽  
G. W. Rahnefeld ◽  
D. R. C. Bailey ◽  
...  
Keyword(s):  
Beef Cattle ◽  
Key Words ◽  
Carcass Traits ◽  
Beef Cows ◽  
Carcass Composition ◽  
Carcass Weight ◽  
Back Cross ◽  
Breed Type ◽  
Bone Content

Breed-of-dam and sex-of-calf effects are reported based on observation of 2007 heifer and steer carcasses. The carcasses were derived from Limousin-sired calves born to dams representing 15 F1 and backcross genotypes reared at two locations over a period of 5 yr. The calves represented Hereford × Angus, Charolais × Shorthorn, Simmental × Shorthorn and all backcross combinations involving Charolais or Simmental with Hereford, Angus or Shorthorn. Carcass traits were analyzed on an unadjusted, a constant hot-carcass weight, and a constant rib-fat depth basis. The slaughter criteria dictated that steers were heavier at slaughter than heifers. They also exhibited higher dressing yield, greater longissimus thoracis area, and lower fat depth. Charolais and Simmental breeding was associated with less rib fat depth, greater longissimus thoracis area, a higher proportion of preferred cuts, less dissectible fat, more bone and more lean in the preferred cuts than British beef breeding. Within the European (Charolais and Simmental) and British beef (Hereford, Angus and Shorthorn) breed groups, breed effects were smaller, but for carcass composition traits they were frequently significant. When compared with Simmental, Charolais breeding tended to be associated with less marbling, less rib fat depth, less dissectible fat and more lean in the preferred cuts. Among the British beef breeds, Hereford was associated with the highest proportion of preferred cuts, Shorthorn with the lowest rib fat depth — but the highest dissectible fat — and Angus with the most marbling, the greatest longissimus thoracis area and the lowest bone content. This research has demonstrated that breed effects for carcass composition traits tend to be additive and that a significant effect may be associated with substitution of as little as one-eighth of the breed composition. Key words: Beef cattle, slaughter traits, carcass traits, breed type, crossbred dam, backcross dam

Growth patterns of first-cross and reciprocal backcross beef cows in two environments

1993 ◽  
Vol 73 (4) ◽  
pp. 805-821
Author(s):  
D. R. C. Bailey ◽  
T. Entz ◽  
G. W. Rahnefeld ◽  
R. M. McKay ◽  
H. T. Fredeen ◽  
...  
Keyword(s):  
Weight Loss ◽  
Beef Cattle ◽  
Environmental Conditions ◽  
Weight Change ◽  
Beef Cows ◽  
Optimal Level ◽  
Growth Patterns ◽  
Intensive Management ◽  
Extensive Range ◽  
Reciprocal Backcross

Growth patterns of first-cross (F1) and reciprocal backcross cows, 3–5 yr old, were evaluated under two contrasting environments: extensive range conditions at Manyberries, Alberta, and semi-intensive management at Brandon, Manitoba. Cows resulting from crossing Hereford (H) × Angus (A), Simmental (S) × Shorthorn (N), Charolais (C) × Shorthorn and reciprocal backcrosses from Charolais × Hereford (CH), Charolais × Angus (CA), Charolais × Shorthorn (CN), Simmental × Hereford (SH), Simmental × Angus (SA), and Simmental × Shorthorn (SN) were evaluated at Brandon. At Manyberries, HA, SN and reciprocal backcrosses of SH, SA and SN were evaluated. All cows were bred to Limousin (L) bulls. Cow weights and backfat estimates were recorded at breeding, calving and weaning. The HA cows were the lightest group for all weigh periods at both locations. At all weigh periods, the SSN (3/4 S 1/4 N) dam crosses at Manyberries and the CCN (3/4 C 1/4 N) and CCH (3/4 C 1/4 H) at Brandon were the heaviest. At Brandon, females gained weight during gestation and usually lost weight during summer nursing. Cows at Manyberries usually gained weight during nursing, with significant gestation weight loss. Nursing status of the cow had a significant effect on weight change, with barren status providing an opportunity for large compensatory gains. The CN dams were significantly heavier at all weigh periods than their 1/4 C back-crosses. At Brandon, the SN dam cross weights exceeded those of their reciprocal backcrosses at breeding, calving and weaning and at calving for the 1/4 S dams. At Manyberries, SN weights exceeded those of the 3/4 S crosses at weaning. Over the duration of study, average backfat estimates for cows at Brandon exceeded those at Manyberries (10.8 and 8.6 mm, respectively). Specific dam crosses performed differently at the two locations, and commercial cattlemen need to closely evaluate the F1 and backcross comparisons to determine the optimal level of performance under their particular management and environmental conditions. Key words: Beef cattle, growth, nursing status, crossbreeding, environment

scholarly journals Milk yield and composition in first-cross and backcross beef cows

1994 ◽  
Vol 74 (2) ◽  
pp. 209-216
Author(s):  
R. M. McKay ◽  
G. W. Rahnefeld ◽  
G. M. Weiss ◽  
H. T. Fredeen ◽  
J. A. Newman ◽  
...  
Keyword(s):  
Beef Cattle ◽  
Key Words ◽  
Milk Yield ◽  
Beef Cows ◽  
Milk Composition ◽  
Weight Changes ◽  
Pasture Management ◽  
Semi Arid

Milk yield and composition from three distinct milkings (spring, August, and fall) were evaluated on first-cross and backcross cows maintained under two contrasting environments. The dam crosses at Brandon (semi-intensive cultivated pasture management) were HA, SN, CN, ACA, CCA, ASA, SSA, HCH, CCH, HSH, SSH, NCN, CCN, NSN, and SSN with H = Hereford, A = Angus, N = Shorthorn, C = Charolais, S = Simmental and a SSA cross was 3/4 Simmental-1/4 Angus. At Manyberries (semi-arid and short grass rangeland) the dam crosses were HA, SN, ASA, SSA, HSH SSH, NSN, and SSN. All cows were bred to Limousin bulls and milkings took place from 1981 to 1985, inclusive. Definitive differences among the backcrosses and between the backcrosses and the F1 crosses were not present. Possible genotupe × environment interactins were observed for milk yield and composition. Milk yield and composition were affected by age of cow and influenced cow and calf weight changes. Key words: Beef cattle, crossbreeding, backcrosses, milk yield, milk composition

19 THE EFFECT OF FOLLICLE-STIMULATING HORMONE IN A MODIFIED CO-SYNCH SYNCHRONIZATION PROTOCOL ON SUBSEQUENT PREGNANCY RATES OF CROSSBRED LACTATING BEEF CATTLE

2013 ◽  
Vol 25 (1) ◽  
pp. 156
Author(s):  
L. R. Gentry ◽  
R. W. Walker ◽  
J. Lambe-Steinmiller ◽  
R. A. Godke ◽  
G. T. Gentry
Keyword(s):  
Treatment Group ◽  
Beef Cattle ◽  
Pregnancy Rate ◽  
Beef Cows ◽  
Subsequent Pregnancy ◽  
Pregnancy Rates ◽  
Reproductive Efficiency ◽  
Follicular Waves ◽  
Estrus Detection ◽  
Synchronization Protocol

Heritability of reproductive traits is relatively low, leaving only management strategies as an alternative to affect reproductive efficiency in beef cattle. The use of assisted reproductive technologies such as fixed-timed AI (FTAI) offers the ability to increase reproductive efficiency through selection of superior genetics and manipulation of calving dates through estrous-synchronization protocols. Application of these technologies has not been fully embraced by cattlemen due to variation in success rate, primarily associated with the apparent lack of control of follicular waves. While it has been reported that an endogenous increase in FSH precedes the emergence of follicular waves in cattle, we could find no reports on the effects of exogenous FSH on FTAI pregnancy rates. Artificial insemination remains the most important reproductive technology that could positively affect cattlemen. Therefore, this experiment was conducted to test the hypothesis that incorporation of FSH into the CO-Synch synchronization protocol would increase FTAI pregnancy rates in beef cattle. Crossbred beef cows (n = 182) with a mean body weight (BW) of 596 ± 6.6 kg and mean body condition score (BCS) of 5.4 ± 0.07 from 3 different locations were stratified across treatment groups by BW, BCS, and days postpartum or cyclicity status based on plasma progesterone concentrations. Females were estrus synchronized using the 7-day CO-Synch+CIDR protocol. All females received a CIDR insert and 100 µg of gonadotropin-releasing hormone (GnRH; Factrel) on Day 0, followed by CIDR removal, 25 mg of prostaglandin (Lutalyse) IM and fitted with an estrus-detection patch (Estrotect) on Day 7. On Day 2, all females (n = 92) in the FSH treatment group were administered 20 mg of FSH (Folltropin) IM and the remaining females (n = 90) served as nontreated controls. Fixed-timed AI was performed at 72 h following CIDR removal when all females were administered 100 µg of GnRH and the estrus-detection patch was evaluated. The overall FTAI pregnancy rate was 55% (100/182) and there was no difference (P = 0.41) in pregnancy rates across locations so the data were pooled and reanalyzed. Pregnancy rates were not affected (P = 0.54) by treatment group and were 52% (48/92) for the FSH-treated females and 58% (52/90) for the nontreated control group. Similarly, based on evaluation of the estrus-detection patch, there was no difference (P = 0.68) in the percentage of females responding to the synchronization protocol [61% (55/92) v. 68% (61/90)] and no difference (P = 0.55) in the pregnancy rate of responding females [62% (34/55) v. 69% (42/61)] for the FSH-treated and nontreated control groups, respectively. In conclusion, administration of FSH 10 days prior to FTAI in CO-Synch+CIDR synchronized crossbred beef cows did not increase subsequent pregnancy rates. However, exogenous FSH administration should be evaluated further to determine its effects, if any, on follicular dynamics related to FTAI in the lactating beef cow.

PREWEANING PERFORMANCE OF CALVES FROM FIRST-CROSS AND RECIPROCAL BACKCROSS COWS

1990 ◽  
Vol 70 (1) ◽  
pp. 35-44 ◽  
Author(s):  
R. M. McKAY ◽  
G. W. RAHNEFELD ◽  
G. M. WEISS ◽  
H. T. FREDEEN ◽  
J. A. NEWMAN ◽  
...  
Keyword(s):  
Beef Cattle ◽  
Key Words ◽  
Range Management ◽  
Intensive Management ◽  
Back Cross ◽  
Extensive Range ◽  
Reciprocal Backcross

Preweaning performance was evaluated for calves out of first-cross and reciprocal back-cross cows maintained under two contrasting environments. All cows were bred to Limousin bulls and the calves were born between 1982 and 1986, inclusive, at Brandon, Manitoba (semi-intensive management) and Manyberries, Alberta (extensive range management). Dam cross comparisons revealed that calves out of Hereford × Angus dams were inferior to calves out of European continental × British dams for all preweaning traits at both locations. Comparisons between calves out of F1 dams and calves out of backcross (1/4 or 3/4 European continental) dams generally favored the calves out of F1 females. Specific and nonspecific comparisons between the reciprocal backcrosses demonstrated that calves out of dams with 3/4 European continental breeding were heavier and grew faster than calves out of dams with 1/4 European continental breeding. Male calves exceeded female calves for all preweaning traits and calves born at Manyberries were heavier and grew faster than calves born at Brandon. Key words: Beef cattle, preweaning growth, crossbreeding, backcrosses

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