About 60 people took part in the clicker survey during the 2017 Oregon Dairy Farmers Association’s Annual Meeting (thank you!). If you’re curious about the results, read on. (Note that not every person answered every question. Also, the duller demographic results are not shown here.)
With regard to who was in the room and their primary roles on or off the farm, we have these results:
Here we have preferences for learning new information:
For those of you who are interested to see what your fellow ODFA members are interested in learning more about, here are the topics surveyed:
Each part consists of an evening classroom presentation at the Oldfield Animal Teaching Facility on the OSU campus, followed by a morning field practical at a local outdoor location.
Class meets Wednesdays (6 – 8:30 pm) and Thursdays (10 – noon). Topics for each month are:
April 19 & 20 – Farm and Forage Assessment
May 24 & 25 – Harvest Management
June 28 & 29 – Irrigation
August 16 and 17 – Fertility
September 20 and 21 – Renovation Techniques
Pre-registration and a $30 fee per part (or a discounted price of $120 for five) per ranch is required. Registration coming soon at http://extension.oregonstate.edu/linn/. If you do not have Internet access, stop by or call the Linn Co. (541-967-3871) or Benton Co. (541-766-6750) OSU Extension Offices for instructions.
Speakers will be Shelby Filley, David Hannaway, Serkan Ates, Gene Pirelli, and Troy Downing, plus other OSU faculty and local experts.
This series will focus on a “project ranch” that we work on together, including site visits and on-line document sharing and blog. The project ranch will be the Wilson Farm, the OSU sheep facility with sheep and cattle grazing the pastures. You can also work on your own ranch as a side project if desired. The objective of the series is to improve knowledge about managing forage on properties in the Willamette Valley.
Hornless calves (named Buri and Spotigy) produced by gene editing. Photo from Carlson et al. 2016 Nature Biotechnology 34:479-481
We know that hornless cattle are safer for people, their herdmates, and themselves. Unfortunately, the combination of polledness and elite genes for other, more critical traits (like milk yield and productive life) don’t often appear in the same animals. We could spend several decades using polled sires to introgress the POLLED allele (allele = version of a gene) into the broader dairy population, but we would sacrifice gains in other traits, because along with the POLLED allele, the calves would get other stretches of less desirable DNA. (However, the nice thing about the POLLED allele is that it’s dominant, meaning that only one POLLED allele is required. At that same location on the other paired chromosome, there can be the horned allele, but we would still have a polled cow.)
You may have heard of gene editing, particularly with a system called CRISPRs. These CRISPR molecules can be introduced into target cells and are capable of recognizing a particular stretch of DNA and cutting at that location. If pieces of DNA containing the desired sequence for that location (e.g., the POLLED sequence) are made available to the cell at the same time, the cell’s DNA repair machinery will use that “new” DNA to repair the break in the chromosome. Voila! That repaired chromosome now contains the DNA sequence we want at that location, instead of the sequence that was originally there.
This type of gene editing has been successfully done in cattle embryos. In this case, the researchers used a more primitive version of CRISPRs called TALENs, but they do the same thing. In embryonic cells from horned cattle, the targeted section of DNA on chromosome 1 was replaced with the POLLED DNA sequence. In this proof-of-concept experiment, clones were created from these cells. And they grew no horns! The rest of the DNA in these animals remained the same as it was in the original genetic source, only the horned/polled location was altered. The two bulls produced (pictured above) will be used in breeding experiments to confirm that their offspring will also be polled.
This precise gene editing technique could be used to introduce polledness into elite dairy sires. In one generation, we could nearly eliminate the need to dehorn/disbud calves. That’s assuming there are no regulatory setbacks regarding the gene editing technology. (Ah, the potential sticking point.)
If you’d like some additional explanation accompanied by video of the polled bulls—currently residing at UC Davis—Science Friday has that here. The paper can be found here on page 479 (Carlson et al. 2016 Nature Biotechnology 34:479-481). I’ve glossed over some of the details, so if you’d like any additional explanation, please post a question via the “Leave a reply” link or email me.
Cattle, like people, can get vitamin D from food and from exposure to the sun. Specifically, vitamin D2 is acquired from plants, while vitamin D3 is synthesized by cells in sun-exposed skin. Vitamin D availability within the body is often measured as the concentration of 25(OH)D in the blood (serum). 25(OH)D is a product of metabolism of both vitamins D2 and D3. With summer sun exposure and no exogenous vitamin D, cows will have 40-100 ng/mL serum 25(OH)D. For cows without the opportunity to graze out on the range all summer, alfalfa hay can provide pretty significant amounts of vitamin D2, and even corn silage contains some. Additionally, vitamin-mineral supplement mixes usually contain vitamin D3, which is metabolized more efficiently than D2.
In a study published last year (full citation below), the investigators compared various management practices with 25(OH)D levels across several herds. Levels of vitamin D in the cows and heifers looked pretty good: all herds had 25(OH)D averages above 30 ng/mL, which is considered the minimum for vitamin D sufficiency. However, the herd that was supplementing at only 20,000 IU/day (rather than the 30,000-50,000 IU/day of the others) did have 22% of their cows below that sufficiency threshold.
The situation for calves in this study wasn’t quite so rosy. Now, newborn calf levels of serum 25(OH)D are typically much lower than in older animals—in this study they averaged 15 ng/mL. In the six herds examined, 25% of newborn calves had serum 25(OH)D concentrations below 10 ng/mL. If left uncorrected, these calves in particular could suffer impaired health. If we look at the figure below, we see distinct differences across farms as the calves age. (We’re looking exclusively at the pre-alfalfa-eating stage here.) Spring/summer sun exposure or supplemental vitamin D in the diet would seem to make a significant difference in a calf’s vitamin D level.
Given that vitamin D is associated with growth, development, and immune function, this nutrient is required starting with a calf’s first days. Most milk replacers contain adequate vitamin D. If raising calves on milk, one should provide supplemental vitamin D3 at a rate of 6000-10,000 IU/kg of dry matter. Additionally, giving calves a 50,000-100,000 IU bolus of vitamin D3 at birth may also be helpful.
(Before initiating a new treatment or nutrition regimen, you should consult your veterinarian/nutritionist.)
(Modified) Figure 4 from Nelson et al. 2016. Serum 25-hydroxyvitamin D [25(OH)D] of Holstein dairy calves according to various housing and nutrition practices. Each point represents the mean and 95% CI of samples from at least 6 calves. The samples collected at 0 wk of age were collected after colostrum consumption. Open triangles (△) and dashed line represent calves from a herd in Idaho fed pasteurized waste milk with no supplemental vitamin D3 limited sun exposure (calves were housed in either hutches or barn and samples were collected in winter). Open circles (○) and dashed line represent calves from a herd in Florida fed pasteurized waste milk with no supplemental vitamin D3 and no direct sun exposure. Filled circles (●) and solid line represent calves in the same herd that received 150,000 IU of vitamin D3 at birth via injection and pasteurized milk supplement that provided 5,000 IU/d. Filled diamonds (◆) and solid line represent calves fed whole milk 3 times/d and kept outdoors in Florida (samples collected in mid-April). Filled squares (■) and solid line represent calves from a herd in Georgia fed milk replacer containing 6,600 IU/kg of DM. The calves received 0.8 kg/d of milk replacer from 0 to 14 d and 1.2 kg/d milk replacer from 15 to 42 d and raised under shade. Filled triangles (▼) and solid line represent calves from a herd in Florida kept outdoors in a group pen and fed ad libitum milk replacer containing 11,000 IU of vitamin D3/kg of DM.
You must be logged in to post a comment.