| Title |
Investigators | Department | Objectives | Approach Keywords | Progress Reports | Impact Statements | Publications | |
Project * COL00651 | |
| Title | Sustainability of Matching Cow Nutrient Requirements With Nutrient Content of Grazed Forages |
| Investigator(s) | Zalesky, DD; Brummer, JE; Whittier, JC; Sharp, R; LaShell, B; LeValley, RB |
| Department | AES Director's Office |
| Objectives | The objectives of this project are to determine the effect of time of calving season on: 1 . performance of beef cows managed to optimize the use of forage production, 2. performance of calves from birth to harvest, 3. profitability and sustainability of matching cows nutrient requirements with nutrient content of grazed forages. |
| Approach | The cow herd at the San Juan Basin Research Center will be randomly split into two calving groups. Group 1 will be bred to calve during the months of March and April while Group 2 cows will be bred to calve during the months of May and June. Replacement heifers for each treatment group will come from heifer calves produced in the respective calving groups. Nutrient requirements of all cows in both treatments will be met according to stage of production nutrient requirements. The following production data wil be collected for cows and calves in both treatment groups: calving data, breeding data, weaning data, and health data. Additionally the nutrient content of the forage base will be tracked as well as the amount of hay produced and its nutrient content. Economic data will also be collected and will include amount of hay fed, amount of supplements fed, labo costs, health costs, gross value of calves produced, cost per calf, net values of calves, cost of hay production and labor costs. The economic and production data will be used to determine which calving season is the most economically viable. |
| Keywords | calving seasons, forage production, cow nutrient requirements, forage nutrient content, profitability, sustainability, cow productivity, calf performance, health, gross value of calves, net value of calves, cost of production |
| Progress Reports | |
| 2001 | Utilizing two different calving seasons will allow an evaluation of the effect of matching cow nutrient requirements with forage nutrient production. Such a comparison will allow for determination of the production and economic advantages and disadvantages of the two systems. Beginning in the May, 2001, the cow herd at the San Juan Basin Research Center were randomly divided by age and breed-type into two treatment groups. Cows in group 1(n= 181) were bred for a traditional March and April calving season with cows in group 2 (n= 188)were bred for a non-traditional May and June calving season. Replacement heifers are included in these numbers and were assigned to treatment groups in the same manner. The cow herd had traditionally calved during March and April. In subsequent years replacement heifers from the respective calving groups will remain in those groups. All cows and heifers were checked for pregnancy utilizing an ultrasound machine in the November, 2001. Conception rates for group 1 and group 2 were 92.0% and 97.0%, respectively. The difference in conception rates are not biologically important at this time since the cows in group 2 had a two month longer postpartum period prior to breeding and the replacement heifers were two months older at breeding. The conception data for this year provides a baseline with subsequent years providing more meaningful data. Body condition score of cows and heifers taken at weaning time were similar for the two groups (5.2, 5.3). The amount of labor and hay being fed to each of the groups is being collected for economic analysis and will continue to be collected over the life of the project. |
| 2002 | In May 2001, the cow herd at the San Juan Basin Research Center was randomly divided by age and breed-type into two treatment groups. Cows in Group I (n=181) were bred for a traditional March and April calving season with cows in Group II (n=188) bred for a non-traditional May and June calving season. Replacement heifers are included in these numbers and were assigned to the treatment groups in the same manner. Subsequently, replacement heifers from the respective calving groups remain in those groups. Conceptions rates for Group I and Group II were 92.0% and 97.0% respectively in 2001 and 93.6% and 85.6% respectively in 2002. A severe drought in 2002 forced a reduction in numbers of calving females in both groups (Group I, n=100, Group II, n=100). The first group of calves born in the respective calving seasons were born in the spring and summer of 2002. Average birth weights for all calves in both groups was similar (38.2 kg). Calving difficulty and calf health following calving was not different between the two calving groups. Death loss during the two calving seasons was similar (2.0%). Due to the severe drought, calves in both calving groups were weaned at an average age of 150 days. Average weaning weights in the fall of 2002 were 157.7 kg for calves in Group I and 161 .8 kg for calves in Group II. Steer calves from both groups were sent to the feedyard at the Colorado State University ARDEC facility for finishing. All heifer calves were retained at the San Juan Basin Research Center as potential replacements. Harvested forages were fed to the two calving groups during 2002. Again, due to the severe drought, more hay was fed to both groups than would normally be fed. At the end of 2002, Group I cows had received a total of 137.4 metric tons of hay while Group II cows had received 68.0 metric tons of hay. |
| 2003 | In May 2001, the cow herd at the San Juan Basin Research Center was randomly divided by age and breed-type into two treatment groups. Cows in Group I (n=181) were bred for a traditional March and April calving season with cows in Group II (n=188) bred for a non-traditional May and June calving season. Replacement heifers are included in these numbers and were assigned to the treatment groups in the same manner. Subsequently, replacement heifers from the respective calving groups remain in those groups. The first group of calves born in the respective calving seasons were born in the spring and summer of 2002. Conceptions rates for Group I and Group II were 92.0% and 97.0% respectively in 2001; 93.6% and 85.6% respectively in 2002; and 90.0% and 84.5% respectively in 2003. A severe drought in 2002 forced a reduction in numbers of calving females in both groups to aproximately 100 head. Additional replacement females were kept in 2003 to begin increasing number of calving females in each calving group. Average birth weights for all calves in both groups were similar in both groups in 2002 (38.2 kg) and 2003 (37.5 vs. 36.6 kg). Calving difficulty and calf health following calving has been similar for both calving groups. Death loss for the two calving groups has been similar (2.0%) for both groups as well. Due to the severe drought in 2002, calves in both calving groups were weaned at an average age of 150 days. Average weaning weights in the fall of 2002 were 157.7 kg for calves in Group I and 161.8 kg for calves in Group II. All steer calves from both groups were sent to the research feedyard at the Colorado State University ARDEC facility for finishing. All calves were weaned at an average age of 205 days in the fall of 2003. Average weaning weights for Group I calves was 238.2 kg and for Group II calves was 231.4 kg. All heifer calves in both groups and for both years (2002, 2003) were retained as potential replacements. Harvested forages were fed to the two calving groups during 2002 and 2003. At the end of 2002, Group I cows had received a total of 137.4 metric tons of hay while Group II cows had received a total of 68.0 metric tons of hay. Total labor inputs are being recorded for each calving group as well as prices received for all sale cattle from each group. |
| 2004 | In May 2001, the cow herd at the San Juan Basin Research Center was randomly divided by age and breed-type into two treatment groups. Cows in Group I (n=181) were bred for a traditional March and April calving season with cows in Group II (n=188) bred for a non-traditional May and June calving season. Replacement heifers are included in these numbers and were assigned to the treatment groups in the same manner. Subsequently, replacement heifers from the respective calving groups remain in those groups. The first group of calves born in the respective calving seasons were born in the spring and summer of 2002. Conception rates for Group I and Group II were 92.0% and 97.0% respectively, in 2001; 93.6% and 85.6% respectively in 2002; 90.0% and 84.5% respectively in 2003 and 96.0% and 95.3% respectively in 2004. A severe drought in 2002 forced a reduction in numbers of calving females in both groups to approximately 100 head. Additional replacement females were dept in 2003 and 2004 to begin increasing the number of calving females in each calving group. Average birth weights for all calves in both groups were similar in 2002 (38.3 kg) and 2003 (37.5 vs. 36.6 kg). Birth weights in 2004 were slightly higher for Group I (41.4 kg) compared to Group II (37.3 kg). Calving difficulty and calf health following calving has been similar for both calving groups. Death loss for the two calving groups has also been similar (2.0%). Due to the severe drought in 2002, calves from both calving groups were weaned at an average age of 150 days. Average weaning weights in the fall of 2002 were 157.7 kg for calves in Groups I and 161.8 kg for calves in Group II. All steer calves from both groups were sent to the research feedyard at the Colorado State University ARDEC facility for finishing. All calves were weaned at an average age of 205 days in the fall of 2003 and 2004. Average weaning weights for Group I calves was 238.2 kg and 247.4 kg, respectively. Groups II calves had average weaning weights of 231.4 kg and 211.8, respectively for the two years. All heifer calves in both groups and for the years 2002, 2003 and 2004 were retained as potential replacements. Harvested forages were fed to the two calving groups during each of the research project years. Total amounts of harvested forages are being recorded for comparison of feed inputs to the two groups. Likewise , total labor inputs are being recorded for each calving group as well as prices received for all sale cattle from each group. |
| 2005 | In May, 2001, the cow herd at the San Juan Basin Research Center was randomly divided by age and breed-type into two treatment groups. Cows in Group I (n=181) were bred for a traditional March and April calving season with cows in Group II (n=188) bred for a non-traditional May and June calving season. Replacement heifers are included in these numbers and were assigned to the treatment groups in the same manner. Subsequently, replacement heifers from the respective calving groups remain in those groups. The first group of calves born in the respective calving seasons were born in the spring and summer of 2002. Conception rates for Group I and Group II were 92.0% and 97.0%, respectively, in 2001; 93.6% and 85.6%, respectively in 2002; 90.0% and 84.5%, respectively in 2003; 96.0% adn 95.3 % respectively in 2004 and 90.6% and 81.5%, respectively in 2005. A severe drought in 2002 forced a reduction in numbers of calving females in both groups to approximatley 100 head. Additional replacement females were kept in 2003 and 2004 to begin increasing the number of calving females in each calving group. Average birth weights for all calves in both groups were similar in 2002 (38.3 kg) and 2003 (37.5 vs. 36.6 kg). Birth weights in 2004 were slightly higher for Group I (41.4 kg) compared to Group II (37.3 kg). Similarly, birth weights in 2005 were slightly higher for Group I (40.0 kg) compared to Group II (31.8 kg). Calving difficulty and calf health following calving has been similar for both calving groups. Death loss for the two calving groups has also been similar (2.0%). Due to the severe drought in 2002, calves from both calving groups were weaned at an average age of 150 days. Average weaning weights in the fall of 2002 were 157.7 kg for calves in Group I and 161.8 kg for calves in Group II. All steer calves from both groups were sent to the research feedyard at the Colorado State University ARDEC facility for finishing. All calves were weaned at an average age of 205 days in the fall of 2003, 2004 and 2005. Average weaning weights for Group I calves was 238.2 kg, 247.4 kg and 246.4 kg respectively for those years. Group II calves had average weaning weights of 231.4 kg, 211.8 kg and 223.6 kg, respectively for those same years . All heifer calves in both groups and for the years 2002, 2003, 2004, and 2005 were retained as potential replacements. Harvested forages were fed to the two calving groups during each of the reserach project years. Total amounts of harvested forages are being recorded for comparison of feed inputs to the two groups. Likewise, total labor inputs are being recorded for each calving group as well as prices received for all sale cattle from each group. |
| 2006 | In May, 2001, the cow herd at the San Juan Basin Research Center was randomly divided by age and breed-type into two treatment groups. Cows in Group I (n=181) were bred for a traditional March and April calving season with cows in Group II (n=188) bred for a non-traditional May and June calving season. Replacement heifers are included in these numbers and were assigned to the treatment groups in the same manner. Subsequently, replacement heifers from the respective calving groups remain in those groups. The first group of calves born in the respective calving seasons were born in the spring and summer of 2002. Conception rates for Group I and Group II were 92.0% and 97.0%, respectively, in 2001; 93.6% and 85.6%, respectively in 2002; 90.0% and 84.5%, respectively in 2003; 96.0% and 95.3 % respectively in 2004 and 90.6% and 81.5%, respectively in 2005; 91.0% and 75.0% in 2006. A severe drought in 2002 forced a reduction in numbers of calving females in both groups to approximately 100 head. Additional replacement females were kept in 2003 and 2004 to begin increasing the number of calving females in each calving group. Average birth weights for all calves in both groups were similar in 2002 (38.3 kg) and 2003 (37.5 vs. 36.6 kg). Birth weights in 2004 were slightly higher for Group I (41.4 kg) compared to Group II (37.3 kg). Similarly, birth weights in 2005 and 2006 were slightly higher for Group I (40.0 and 38.2 kg, respectively) compared to Group II (31.8 and 35.0 kg, respectively). Calving difficulty and calf health following calving has been similar for both calving groups. Death loss for the two calving groups has also been similar (2.0%). Due to the severe drought in 2002, calves from both calving groups were weaned at an average age of 150 days. Average weaning weights in the fall of 2002 were 157.7 kg for calves in Group I and 161.8 kg for calves in Group II. All steer calves from both groups were sent to the research feed yard at the Colorado State University ARDEC facility for finishing. All calves were weaned at an average age of 205 days in the fall of 2003, 2004, 2005 and 2006. Average weaning weights for Group I calves was 238.2 kg, 247.4 kg, 246.4 kg and 243.0 respectively for those years. Group II calves had average weaning weights of 231.4 kg, 211.8 kg, 223.6 kg and 219.2 kg, respectively for those same years. All heifer calves in both groups and for the years 2002, 2003, 2004, 2005 and 2006 were retained as potential replacements. Harvested forages were fed to the two calving groups during each of the research project years. Total amounts of harvested forages are being recorded for comparison of feed inputs to the two groups. Likewise, total labor inputs are being recorded for each calving group as well as prices received for all sale cattle from each group. |
| Impact | |
| 2001 | Results of this study will help determine if matching cow nutritional requirements with optimal forage nutrition is more economically viable. The project will evaluate production as well as economic aspects of the two calving seasons. |
| 2002 | Continued evaluation of matching cow nutritional requirements with optimal forage nutrition will assist in determing the economic viability of the two different calving seasons. Early results would indicate that a significant reduction in harvested forages fed may be realized. No reductions in production traits have been determined at this time. |
| 2003 | Continued evaluation of matching cow nutritional requirements with optimal forage nutrition will assist in determining the economic viability of the two different calving seasons. Early results would indicate that a significant reduction in harvested forages fed may be realized. A trend in reduced conception rates for Group II cows may be appearing. Also a reduction in average weaning weights may also be present for calves in the later calving group. |
| 2004 | Continued evaluation of matching cow nutritional requirements with optimal forage nutrition will assist in determining the economic viability of the two different calving seasons. Early results would indicate that a significant reduction in harvested forages fed may be realized. A trend in reduced conception rates for Group II cows may be appearing, although conception rates in the fall of 2004 were similar. Also a reduction in average weaning weights may also be present for calves in the later calving group. Both the redections in conception rates and weaning weights for calving group II may have been impacted by the drought situation that occurred during 2002 and 2003. It will be important to see if both of these traits return to levels similar to calving group I. |
| 2005 | This project continues to evaluate the economic viability of the two different calving seasons . Results indicate that a potentially significant reduction in harvested forages fed may be realized. A fairly consistent trend in reduced weaning weights for Group II calves has been present, but may be offset by higher prices when sold at weaning. There also appears to be a trend for reduced conception rates for Group II females, although the conceptin rates in 2004 were similar. While the reductions in conceptions and weaning rates for Group II were most likely impacted by the drought in 2002 and 2003, these averages have not returned to levels similar to Group I. It will be important to continue evaluation of these traits during the final year of the project. |
| 2006 | This project continues to evaluate the economic viability of the two different calving seasons . Results indicate that a potentially significant reduction in harvested forages fed may be realized. A fairly consistent trend in reduced weaning weights for Group II calves has been present, but may be offset by higher prices when sold at weaning. There also appears to be a trend for reduced conception rates for Group II females, although the conception rates in 2004 were similar. While the reductions in conceptions and weaning rates for Group II were most likely impacted by the drought in 2002 and 2003, these averages have not returned to levels similar to Group I. It will be important to continue evaluation of these traits during the final year of the project. |
| Publications | |
| 2006 |
Comparison of Pre-weaning Growth Traits for Early and Late Spring Calving. D.D. Zalesky, B.A. LaShell and D.R. Selzer. 2006 Animal Sciences Research Report. |