Kilograms Of Calf Research Articles

Influence of frame size and body condition score on performance of Brahman cattle.

The effects of frame size (FS) and body condition score (BCS) on performance of Brahman cows were evaluated using records collected from 1984 to 1994 at the Subtropical Agricultural Research Station, Brooksville, Florida. Age at puberty (AP), calving rate (CR), calving date (CD), survival rate (SR), weaning rate (WR), birth weight (BWT), weaning weight (WWT), preweaning ADG, and kilograms of calf produced per cow exposed (PPC) were obtained from first- (n = 215), second- (n = 130), and third or greater-parity (n = 267) dams. Based on hip height at 18 mo of age, heifers were assigned to three FS groups: small (115 to 126 cm), medium (127 to 133 cm), or large (134 to 145 cm). Small and medium FS heifers attained puberty at younger (P<.05) ages (633.2+/-12.3 and 626.4+/-12.0 d) than large FS heifers (672.3+/-17.1 d). Calving rate in large FS second-parity dams was 27% less (P<.05) than in small and medium FS dams. In third or greater-parity dams, CR was greater (P<.05) for small FS cows than for medium and large FS cows. Across the three parity groups, CR improved with increasing BCS. Except for the first-parity dams, animals with better fall BCS calved earlier (P<.05). In first-parity dams, SR was less (P<.01) in large (47.9+/-11.0%) than in small (80.7 +/-5.2%) and medium (83.4+/-4.7%) FS groups. Weaning rates of large FS first- and second-parity dams were less (P<.05) than those of small and medium FS dams. Second-parity dams with BCS 3 had lower (P<.05) WR than dams with BCS 4 and 5. Within first- and third or greater-parity dams, BWT of calves born to small FS cows were the lightest, and those born to large FS dams were the heaviest; those born to medium FS dams were intermediate (P<.05). In second-parity dams, BWT of calves of large FS dams were greater (P<.05) than those of small and medium FS dams. In first-parity dams, calves weaned by small FS cows had lower (P<.05) WWT than those weaned by higher FS cows. In the third or greater-parity group, large FS dams weaned heavier calves (P<.05) than other dams. In all parity groups of dams, calves out of large FS cows had greater ADG (P<.05) than those from small and medium FS cows. In first-parity dams, PPC was comparable between small and medium FS dams, but both tended to be greater (P<.10) than PPC of large FS dams. Small and medium FS females reached puberty at an earlier age, calved earlier, and had greater calving, survival, and weaning rates, as well as greater kilograms of calf produced per cow exposed than the large FS females. As the large FS cows matured, they seemed to have overcome the negative effects imposed by FS that were observed at younger ages. Their performance traits were generally all comparable to those of smaller cows once they had reached maturity.

Evaluation of biological efficiency of free-grazing beef cows under semidesert conditions.

Effects of cow BW, hip height, and estimated genetic potentials (EBV) for weaning weight direct and milk on cow productivity, fecal OM output, OM intake, and efficiency (kilograms of calf BW/kilogram of OM intake by the cow) were evaluated with 44 free-grazing crossbred cows under semidesert conditions. Calf BW were measured during early, mid-, and late lactation. Data were collected in four periods: Period 1 = late spring (early lactation), Period 2 = late summer (mid-lactation), Period 3 = mid-autumn (late lactation), and Period 4 = mid-winter (nonlactation). Calf BW increased linearly with cow BW (P < .01) in Periods 1, 2, and 3. Fecal OM output and OM intake increased with cow BW in Periods 2 (P < .01) and 4 (P < .01), and on average (P < .02). Overall efficiency decreased with increasing cow BW (P < .04). Taller cows excreted more fecal OM and had greater OM intake throughout the study (P < .02 to P < .11). Overall efficiency decreased with increasing cow hip height (P < .05). Weaning weight direct EBV of cows was related linearly to cow BW (P < .01 to P < .07) and to calf BW (P < .01 to P < .07). Calf weight in all periods increased linearly with milk EBV (P < .001). Overall, fecal OM output, OM intake, and efficiency were not affected by milk EBV.

The economic effect of estrus synchronization in beef heifers on average weaning weight of calves

Prostaglandin was used to induce estrus in 129 Hereford × Holstein heifers for artificial insemination. At the start of the breeding season heifers were observed twice daily and inseminated 12 hours after first being observed in estrus. On the morning of the sixth day of the breeding season all heifers not yet observed in estrus or inseminated were treated with prostaglandin (25 mg Lutalyse R). Observation was continued and heifers were bred 12 hours after first observed in estrus. Of the 129 heifers 33 were inseminated before prostaglandin treatment, the remainder of the heifers were bred within 4 days of treatment. Two heifers developed cysts and did not express estrus. First service pregnancy rates were 70% before treatment and 79% after treatment. All heifers were inseminated the first time within the first 10 days of the breeding season and 100 pregnancies occurred in the first 10 days of the season. As a result median days to pregnancy was 8. Calves were all weaned and weighed at approximately 150 days of age. These results were then used to model the economic impact of estrus synchronization of beef heifers on the increased weaning weights of their calves. Prostaglandin treatment altered the distribution of pregnancies and resulted in a cluster of conceptions from Day 7 to 10 of the breeding season with no conceptions from Day 11 to 19. In order to study the influence of estrus synchronization on weaning weights a simulation model was constructed. All heifers that conceived on the first service after prostaglandin were assigned an alternate date of conception from Day 7 to 21 of the breeding season with a random number generator. In this way a uniform random distribution of pregnancies over the first 21 days of the breeding season was constructed. An alternate calving date was then estimated using the known gestation length and this date was used to calculate the weaning weight of the calf using the known weight per day of age. The average weaning weight of the uniform random distribution was then compared to the synchronized distribution with Student's t -test. The simulation model was repeated 10 times and each time weaning weights of the uniform random distribution were significantly less than with the synchronization program (p<.01). At a value of $4.00 for prostaglandin and $1.76 for each kilogram of calf the average increase of 3.8 kgs in weaning weight per calf resulted in a return on investment of $1.92 for every dollar invested in prostaglandin.

GROWTH, PRODUCTION AND REPRODUCTION CHARACTERISTICS OF THE CANADIAN BREED OF CATTLE AND ITS FIRST CROSS AND BACKCROSS WITH BROWN SWISS. II. PRODUCTION AND REPRODUCTION

Milk and fat production, number of inseminations per conception, age and weight at calving and kilograms of calf born were studied on 21 Canadian (C); 25, 3/4C 1/4 Brown Swiss (3/4C) and 22, 1/2C 1/2 Brown Swiss (1/2C) cows raised at the Deschambault station and 20 cows each of C and 1/2C raised at the La Pocatiere Station. The cows were born between 1973 and 1977 and producted from 1975 to 1981 inclusive. Average 305-day milk production for the first two lactations was 4746 kg for 1/2C, 18% higher than 3/4C and 29% higher than C cows at Deschambault and 26% higher than C cows at La Pocatiere (P &lt; 0.01). At Deschambault, fat percentage was 4.8% in C cows, 8 and 4% higher (P &gt; 0.05) than in 1/2C and 3/4C cows, respectively. However, at La Pocatiere, fat percentage was similar in the C and 1/2C groups. In the 3/4C and 1/2C crosses at Deschambault, milk production increased 14.5 and 16.4% in second and a further 7.8 and 12.3% in third lactations. For C cows, the increase was 11.6 and 7.6% at Deschambault and 16.7 and 14.6% at La Pocatiere, respectively. C cows needed 0.23 and 0.34 less inseminations than 1/2C at Deschambault and La Pocatiere, respectively (P &gt; 0.05). Twinning rate was 2.6, 2.8 and 6.2% for C, 3/4C and 1/2C cows, respectively. The higher twinning rate of 1/2C cows and a 1.6 kg heavier calves they produced resulted in an average of 2.3 kg more calves born than from C cows. The 1/2C cows were 23 and 31 days younger (P &gt; 0.05) and 10 and 12% heavier (P &lt; 0.01) at calving than C cows at Deschambault and La Pocatiere, respectively. The 3/4C cows were intermediate. There were significant differences between Deschambault and La Pocatiere stations, the performance at the former station being better. Lactation number and season of calving had significant effects on milk production. Key words: Canadian cattle, crossing with Brown Swiss, milk and fat production, reproduction

Beef X beef and dairy X beef females mated to Angus and Charolais sires II. Calf growth, weaning rate and cow productivity.

Preweaning growth of 814 progeny was studied, and weaning rate and kilograms of calf weaned/cow exposed were determined for 310, 2- to 7-yr-old angus x Hereford (AH), Charolais X Hereford (CH), straight bred Hereford (HH) and Brown Swiss X Hereford (SH) cows mated to Angus and Charolais bulls. Charolais-sired calves grew more rapidly (P less than .01) then Angussired calves were heavier (P less than .01) at 130 and 210 d of age. Progeny of SH females grew faster (P less than .05) and were the heaviest at 130 (164 kg) and 210 (231 kg) d, whereas calves from HH dams grew the slowest and weighed the least (P less than 0.5) at 130 (125 kg) and 210 (180 kg) d of age. Progeny from AH and CH dams had similar 130-d weights (CW130) and made similar daily gains from birth to 130 of age (ADGI). Calves from CH females gained faster (P less than .05) from 130 to 210 d (ADG2) and had higher (P less than .05) 210-d weights (CW210) than did calves from AH dams. ADG1 and ADG2 of male calves were .043 and .072 kg/d greater, respectively (P less than .01) than those of heifer calves. Age of dam influenced (P less than .01) calf preweaning gains and weights. Calves from 4- to 7-yr old cows had greater (P less than .05) ADG1 and ADG2 and higher (P less than .05) CW130 and CW210 than progeny of younger dams. Progeny of 2-yr-old cows grew more slowly (P less than .05), and were last (P less than .05) in all traits (ADG1, ADG2, CW130 and CW210), whereas progeny of 3-yr-old cows were intermediate to those of 2 and 4- to 7-yr-old females. Cow breed type influenced (P less than .01) weaning rate (WR) and kilograms of calf weaned/cow exposed. SH females has the highest WR (83.4%), AH and CH were intermediate at 76 .8 and 77.7%, respectively, and HH dams had the lowest (P less than .05) WR, 66.4 calves/100 cows exposed. SH cows weaned 34.6 kg more (P less than .05) calf/cow exposed than AH and CH dams. HH dams were least productive (P less than .05), weaning 122.3 kg calf/cow exposed. Dairy X beef dams (SH) weaned 47.6 kg more (P less than .01) calf/cow exposed than the average of beef X beef dams (AH, CH, HH). Dairy X beef females had the highest WR and weaned the heaviest calves.

Long-Term Effects of Winter Supplement on the Productivity of Range Cows

For 10 consecutive winters, beginning at the age of 8 months, 120 Hereford females were fed Low, Moderate, High and Very High levels of supplement to determine the long-term effects of level of winter supplement on the productivity of beef cows. In addition, one half of the Very High level cows were switched to the Moderate level after three winters. In the first four calf crops high levels of supplement resulted in earlier (P<.025) calving dates. Increasing supplement from the Low to High levels resulted in larger birth weights in calf crops one (P<.001), two (P<.025), three P<.025) and nine (P<.025). Birth weights of calves from Very High level cows that were switched to the Moderate level tended to parallel birth weights of calves from cows on the Moderate level, whereas birth weights of calves from cows remaining on the Very High level were lower until the sixth calf crop. Calving percentages declined in the calf crops two and three, but all treatment groups had similar values in calf crop four and succeeding calf crops. Very High level females weaned only 66.3% of their calves in calf crop one, the other 33% were stillborn. After the first calf crop, High level females weaned more kilograms of calf per cow exposed than any other group. Differences among the Low, Moderate and High groups decreased rapidly through the third calf crop, and values for these groups remained similar for calf crops four through nine. Weighted average calving percent data through nine calf crops indicated that the Low (91.4%) and Very High (92%) groups ranked lower than the Moderate (95.5%), High (95.1%) and Very High Moderate (97.5%) groups. The weighted average weaning percentages were slightly lower for the Very High groups than for the other four groups. The treatment rank of kilograms of calf weaned per cow exposed was High (197), Moderate (187), Very High-Moderate (184), Very High (177) and Low (176).