Newsletter – 2016 – August
Message from the President’s Desk:
By Dr. Stephen LeBlanc
Make your plans to attend the DCRC Annual Meeting November 10 – 11 in Columbus, Ohio. The program committee led by Dr. Matt Utt has put together an outstanding line-up of topics and speakers, as well as some innovative panel discussions with leading producers and advisors. Registration is open—be sure to check out the full program. Discounted rates are available if you register before October 1.
Be seen supporting DCRC. We have arranged an online storefront with Land’s End for DCRC-branded apparel. Choose from hundreds of items in many colors and styles to suit your taste while shopping from the comfort of your location. Once you make your selection, the DCRC logo will be added to your item—helping to promote our organization. Visit the store.
Whether you wear DCRC attire or not, we need your help to keep spreading the word about the benefits of membership. Tell a colleague or a client about DCRC. If you’re coming to the annual meeting, why not make it a road trip with some of your clients, employees or neighbors? The program will provide a wealth of information for all who attend, and the travel time gives you a chance to talk about implementing ideas that you have gathered.
DCRC thrives because of the generous investment of energy and ideas by our board and committee members. Would you consider serving to help advance cow fertility and health in our industry? You will work with a group of keen people who share your passion for successful management and giving back to dairy farming. Please speak with a board member or contact us at email@example.com for more information or to volunteer your time.
As with many organizations, success is the result of good work behind the scenes. Our administrative support person at FASS for the last two years, Kelsey Grant, is moving to a new career opportunity at the end of August. We thank Kelsey for her work to help DCRC run smoothly and we wish her the best in her new position.
See you in Columbus!
See you in Columbus!
If you haven’t already done so, make your plans now to attend the DCRC Annual Meeting November 10 – 11 in Columbus, Ohio. The program committee has put together another outstanding line-up of topics, speakers and innovative panel discussions with leading producers and advisors. Don’t miss it! Registration is open—be sure to check out the full program.
Discounted rates are available if you register before October 1.
Wear your Support for DCRC on your Sleeve
DCRC is excited to announce that we now have an online storefront with Land’s End for DCRC-branded apparel. Choose from hundreds of items in a wide range of colors, styles and sizes to suit your taste while shopping at your convenience. Once you make your selection, the DCRC logo will be added to the item—helping to promote our organization everywhere you go!
Visit the store or call (866) 711-2103.
Does Heat Stress in Utero Affect Calf Fertility?
Calves born to cows exposed to heat stress during the dry period have lower birth weight and weaning weight and compromised passive immune transfer compared with those born to dams that are cooled.
Researchers in Florida recently set out to determine if heat stress in utero has carryover effects after weaning. The results were published online August. 10, 2016, by the Journal of Dairy Science.
Cooled cows were housed with sprinklers, fans and shade, whereas only shade was provided to heat-stressed cows. All calves were managed in the same manner and weaned at 49 days of age.
- Calves from heat-stressed dams were lighter at birth than calves from cooled dams. But, no effect of treatment was observed on age at first artificial insemination (A.I.) and age at first calving.
- Compared with heifers from cooled cows, heifers from heat-stressed cows had a greater number of services per pregnancy confirmed at day 30 after A.I., but no treatment effect was observed on number of services per pregnancy confirmed at day 50 after A.I.
- A greater percentage of heifers from cooled cows reached first lactation.
- Heifers from heat-stressed cows produced less milk up to 35 weeks of the first lactation.
These data suggest that heat stress during the last six weeks of gestation induces a phenotype that negatively affects survival and milk production up to and through the first lactation of offspring.
GnRH Prior to First Insemination May Help with Heat Stress
Researchers in Kansas recently compared ovarian responses, pregnancy per artificial insemination (A.I.) and pattern of insemination of estrus detection-based presynchronization protocols before first A.I. during heat stress. The results will be published in a future issue of the Journal of Dairy Science.
The researchers randomly assigned 1,358 cows from three dairies to two treatments following a 60-day voluntary waiting period. Cows either received a dose of GnRH on the first day of the study or no treatment on that day. Progesterone was increased on study day seven for the cows receiving GnRH.
In a second experiment, 1,971 cows from three dairies were assigned randomly to two treatments following 49 days in milk, similar to the first experiment. In both experiments, prostaglandin injections were administered 14 days apart starting on study day seven for all cows. Cows not inseminated after detection of estrus were submitted to a timed artificial insemination protocol at study day 35.
Results show that cows that received the dose of GnRH became pregnant at a faster rate than control cows.
The researchers conclude that GnRH-based presynchronization protocols begun before the end of the voluntary waiting period may benefit the reproductive efficiency of estrus detection-based programs during heat stress. In addition, treatment with GnRH decreased the prevalence of anovular cows at the initiation of prostaglandin injections.
Heat Stress Does Affect Bull Fertility
Researchers in Brazil recently discovered that selected sperm traits are simultaneously altered after scrotal heat stress occurs. Furthermore, these traits play specific roles in in vitro fertilization and embryonic development. The findings were published in the September Journal of Theriogenology.
In the trial, bulls were exposed to scrotal heat stress. Following this exposure, sperm were analyzed for alterations as well as performance in in vitro fertilization and embryonic development.
Results show scrotal heat stress induced alterations in all evaluated sperm head features, as well as cleavage and blastocyst rates. The researchers conclude that several sperm traits were simultaneously altered as a result of a thermal insult. These sperm traits likely play specific roles in in vitro fertilization and embryonic development. The results indicate the importance to protect herd sires from heat stress.
How does Postpartum Metabolism Influence Reproduction?
It’s an obvious understatement to say that there’s a lot going on within a cow’s systems following calving.
Transitioning from the dry period to lactation requires a high-producing dairy cow to drastically adjust her metabolism so that nutrients can be partitioned to support milk production, a process referred to as homeorhesis.1
At the same time, her body undergoes uterine involution and ovarian activity is resumed. These processes can be at odds with milk production, particularly if the unique processes that occur in early lactation become imbalanced and the cow experiences negative energy balance and/or metabolic disease during this timeframe, notes Matt Lucy, University of Missouri professor of Animal Science.
“A potential end result is that the cow does not become pregnant during the breeding period,” Lucy says. “There is ample evidence that the hormones responsible for the homeorhetic mechanisms that support lactation can also act on the uterus and ovary to affect their function prior to and during the breeding period.”
Reproductive failure may occur because a sharp increase in nutrient requirements generally occurs as lactation begins—which is when feed intake is usually depressed. The imbalance causes extensive mobilization of body tissues, particularly body fat, but also amino acids, minerals and vitamins.
Despite tight homeostatic controls and homeorethic adjustments to cope with the changes in metabolism caused by milk production, 45 percent to 71 percent of dairy cows across different levels of milk production, breeds and management systems develop metabolic and infectious diseases in the first months of lactation.2
Importance of Glucose
Glucose is an important factor in these processes. First, because of its purpose as a major component of cows’ milk and second, because it’s a molecule that coordinates homeorhetic mechanisms that could possibly interrupt postpartum uterine health and pregnancy.
While a series of mechanisms are in place to ensure glucose levels, the postpartum cow has chronically low blood glucose concentrations because she fails to meet the glucose requirement.3This failure matters because glucose has an impact on whole animal metabolism—likely through its capacity to affect changes in endocrine hormones like insulin.
Figure 1. Metabolic processes in the early postpartum cow with potential to link glucose to the reproductive system. Glucose is synthesized in the liver via gluconeogenesis from substrates arising from rumen fermentation and the catabolism of muscle and adipose tissue. Glucose may ultimately control both circulating insulin (directly) and liver IGF1 production (via insulin-stimulated IGF1 synthesis and secretion). Glucose is also a required substrate for lactose synthesis during the production of milk. Low circulating glucose may impair reproductive processes that are needed to re-establish pregnancy during early lactation.3
“When we examined blood glucose concentrations in early postpartum cows we found that those that became pregnant after first artificial insemination (A.I.) had greater blood glucose concentrations on the day of calving and at three days postpartum when compared with cows that did not become pregnant,” explains Lucy.
A relationship between serum nonesterified fatty acid (NEFA) concentrations and subsequent pregnancy also existed (cows that became pregnant at first A.I. had lower postpartum NEFA concentrations when compared with cows that did not become pregnant at first A.I.).
“In an attempt to address the possibility that glucose is the primary metabolic driver of the entire system we infused glucose into early postpartum cows in a physiologically relevant manner,” says Lucy. There was a marked decrease in both NEFA and beta-hydroxybutyric acid (BHBA) in response to glucose infusion.”
In addition, the glucose infusion increased circulating IGF1 concentrations. The researchers theorize that insulin may have mediated the stimulatory effects of glucose on IGF1.
Based on these results, it is possible that glucose entry rate relative to demand in early lactation is coordinating the homeorhetic mechanisms. These same mechanisms may be impacting the reproductive systems that are undergoing restoration during the first 30 days postpartum.
Short- and Long-term Implications
Most of the available data indicate that metabolic profile of the prepartum cow is equally important to that of the postpartum cow for subsequent uterine health and/or the establishment of pregnancy.
“Using an index that was developed for categorizing physiological imbalance, researchers concluded that an index that included NEFA, BHBA, and glucose was predictive of postpartum uterine disease, especially when the index was used prepartum,” says Lucy. In all likelihood the metabolic profile associated with uterine disease is initiated before or shortly before calving.
This is not surprising given the relatively acute nature of the physiological events at the time of calving and the homeorhetic mechanisms at the initiation of lactation. A cow’s homeorhetic capacity and her inherent resistance to disease are largely manifested after calving but the underlying biology is theoretically in place before calving.
Additionally, low concentrations of glucose in postpartum cows may predispose the cow to pregnancy loss because the placenta may not have adequate substrate for the creation of new cells. The incompetent and slowly developing placenta may eventually compromise the fetus.
Does this mean dairy farmers should adjust feeding strategies to influence postpartum glucose levels? After all, feeding more dietary starch or enhancing the ruminal fermentability of starch in the diet usually results in increased plasma insulin concentrations.1
For example, research4 conducted in 2002 examined feeding cows of low and high genetic merit diets that differed in the ability to induce high or low insulin concentrations in plasma. Feeding the high-starch diet reduced the interval to first postpartum ovulation and resulted in a greater proportion of estrous cyclic cows within the first 50 days postpartum.
However, responses have been inconsistent. Also, keep in mind that while diets high in starch favor increases in plasma insulin, excessive amounts of readily fermentable starch have the potential to suppress dry matter intake and offset any potential benefits of dietary manipulation on ovarian function.1
For now, be aware of the role glucose plays in the endocrine and metabolic environment of the lactating cow—and how that affects the capacity of the cow to become pregnant postpartum.
Also important, but less clear, are the mechanisms that link lactation to a predisposition for pregnancy loss in the lactating cow. The slow rate of embryonic or fetal growth in lactating cows with low blood progesterone and low blood glucose concentrations may be an important mechanism explaining pregnancy loss.
1 Santos JEP, Bisinotto RS, Ribeiro ES, Lima FS, Thatcher WW. Impacts of Metabolism and Nutrition During the Transition Period on Fertility of Dairy Cows. In Proceedings, 2012 High Plains Dairy Conference. Available at: http://www.highplainsdairy.org/2012/20_Santos_Impacts%20of%20Metabolism%20and%20Nutrition_2012%20HPDC_Final.pdf. Accessed August 5, 2016.
2 Santos JEP, Ribeiro RS. Impact of animal health on reproduction of dairy cows.Animal Reproduction. 2014;11(3):254–269.
3 Lucy MC. Mechanisms Linking Postpartum Metabolism with Reproduction in Dairy Cows. In Proceedings, 2015 Florida Ruminant Nutrition Symposium. Available at: http://dairy.ifas.ufl.edu/rns/2015/05.%20Lucy.pdf. Accessed July 28, 2016.
4 Gong JG, Armstrong DG, Baxter G, Hogg CO, Garnsworthy PC, Webb R. The effect of increased dietary intake on superovulatory response to FSH in heifers. Theriogenology 2002;57:1591-1602.
Dr. Divakar Ambrose, BVSc, MVSc, Ph.D.
Professional Animal Scientist (PAS; American Registry of Professional Animal Scientists),
Professional Agrologist (PAg; Alberta Institute of Agrologists)
Edmonton, Alberta, Canada
DCRC Member since 2007
I am a Dairy research scientist within the Livestock Research Section of the Ministry of Agriculture and Forestry, Government of Alberta. I am also a professor at the Department of Agricultural, Food and Nutritional Science, University of Alberta.
My organization is responsible for the policies, legislation, regulations and services necessary for Alberta’s agriculture, food and forest sectors. One of its mandates is to collaborate with industry and post-secondary institutions on targeted research projects that enhance growth and environmental stewardship and promote innovation in the agriculture and forest sectors.
As a research scientist and professor with a research focus on dairy cattle reproductive physiology and management, I conduct original, applied and adaptive research with a goal to improve reproductive efficiency of dairy herds. My primary responsibility is research, with a smaller commitment to extension and teaching. I work with a 150-cow research herd at the University of Alberta and also conduct research on commercial dairy farms in the province of Alberta.
Research interests include:
- Control of ovarian function (synchronization of estrus and ovulation)
- Improving estrus detection efficiency through electronic aids (activity monitoring systems and infrared thermography)
- Influence of nutrition on reproduction (e.g., omega-3 fatty acids, starch)
- Strategies to reduce early embryonic mortality
- Postpartum reproductive management (anestrus, cystic ovaries, endometritis)
- Reproductive benchmarking using in line milk progesterone data
- Exploring new reproductive phenotypes of value for genetic selection
I co-teach an undergraduate course on dairy production at the University of Alberta and supervise graduate students.
Dairy Interest and Experience
I was born and raised in India. Although my parents were employed in their own professions, they were hobby farmers at heart, raising livestock (dairy cows, goats, chicken and turkeys) in the backyard of our family home. We also had several pet dogs and cats in the house at all times.
Clearly, my parents’ interest in livestock and pets triggered my passion for animals. I trained as a veterinarian in India and provided veterinary and animal husbandry services to rural dairy farmers for a short time before moving on to graduate studies and research.
As a young veterinarian serving the Indian dairy industry in the 1980s, I was first exposed to reproductive problems in dairy animals (zebu and cross-bred cattle and water buffaloes). This exposure to an industrywide problem and my desire for graduate study and research led me to take up clinical research on postpartum metritis for my Master of Veterinary Science degree. After completing my master’s, I was engaged in a dairy extension program for more than a year, which further exposed me to the problem of poor reproductive efficiency in dairy cattle.
My next position was with the Indian Council of Agricultural Research which gave me an opportunity to be involved in the then emerging field of embryo transfer in cattle. After being actively engaged in bovine embryo transfer and in vitro fertilization research for a few years, I came to Canada for my Ph.D., again with a focus on dairy cattle reproduction.
After earning my Ph.D. from the University of British Columbia (Adviser: Professor Raja Rajamahendran), I was fortunate to take up my postdoctoral studies at the University of Florida under professor Bill Thatcher, developing strategies to improve fertility in heat-stressed dairy cattle.
DCRC’s Influence and Contribution
I believe DCRC already has an influence on international dairy reproduction education and dairy management practices through its offerings of excellent summary topics, webinars and protocols online. I notice that webinars are also available in Spanish which will be very useful to its South American audience.
DCRC could make further contributions to international dairy improvement by establishing formal knowledge transfer collaborations with veterinary schools and universities offering animal science programs.
I really enjoy the small meeting format of DCRC which allows for better interactions with fellow researchers, veterinarians and producers.
The DCRC webinars are also great continuing education tools which are available online for access anytime, from which I’m sure I have learned many things. In addition, the research summaries and other resources available online are all valuable sources of new information.
I often direct my students and industry contacts to the DCRC protocols summary sheet as a quick reference guide.
Reproductive Challenges Ahead
Although at an individual producer level, I often hear about anestrus, cystic ovaries and metritis being problems, I believe poor estrus detection efficiency and high early embryonic losses are the biggest challenges. As more and more producers choose activity monitoring systems, we can expect improvements in estrus detection.
- DCRC Webinar, Improving Facilities to Optimize Cow Comfort, August 26, 1 p.m. (Central Time)
- American Association of Bovine Practitioners 49th Annual Conference, September 15 – 17, Charlotte, North Carolina.
- All-American Dairy Show, September 17 – 22, Harrisburg, Pennsylvania.
- Minnesota Nutrition Conference, September 21 – 22, Prior Lake, Minnesota.
- World Dairy Expo, October 4 – 8, Madison, Wisconsin
- 78th Annual Cornell Nutrition Conference, October 18 – 20, East Syracuse, New York.
- 2016 Penn State Dairy Nutrition Workshop, November 9 -10, Grantville, Pennsylvania.
- DCRC Webinar, Assessing Reproductive Efficiency, October 28, 1 p.m. (Central Time)
- DCRC Annual Meeting, November 10 – 11, Columbus, Ohio.
- National Mastitis Council 56th Annual Meeting, January 29 – 31, St. Pete Beach, Florida.