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Dairy Science

Title Summary Date ID Author(s)
"Waste" Milk For Calves Jun 30, 2014
A Decision-Making Tool to Determine the Feasibility of Purchasing Virginia Milk Commission Base Jan 10, 2014 DASC-30P
A Youthful Approach to Keeping Dairy Records Aug 25, 2014
Agronomy Handbook, 2000 May 1, 2009 424-100
Ammonia Emissions and Animal Agriculture

Agricultural producers are under constant pressure to minimize the impact their management practices have on the environment. Although most environmental concerns related to animal agriculture have focused on water quality during the past two decades, air quality issues have become an increasing concern. Odors have been the main air quality concern related to agricultural animal production. However, ammonia emissions from livestock and poultry operations have recently received significant attention. New air quality standards that cover ammonia emissions in the United States were adopted in 1997. These regulations will have a significant impact on the future of animal production operations. The purpose of this publication is to provide an overview of ammonia production associated with animal agriculture and to explain why it is receiving greater attention from those concerned with environmental quality.

May 1, 2009 442-110
Calf Nutrient Requirements During Cold Weather Jan 7, 2014
Cleaning and Sanitizing Milking Equipment

All milking equipment, lines, and utensil surfaces that come into contact with milk or dirt or manure must be thoroughly cleaned and sanitized before the next milking. Bulk milk tanks also must be cleaned after each milk pickup. and sanitized before the next milking. The purpose of cleaning is to remove milk soils, organic and mineral solids that form on equipment surfaces after the milk is removed. The purpose of sanitizing is to kill residual microorganisms present on these surfaces immediately prior to milking. Inadequate or improper cleaning or sanitizing or both allows bacteria to remain on equipment surfaces and to grow and multiply. This results in elevated bacteria counts in milk

May 1, 2009 404-400
Cooling Cows: Not Just The Milking Herd Apr 24, 2014
Culling Patterns Can Tell A Story Jan 7, 2015
DHI Somatic Cell Count Program Guidelines
Somatic cell counts (SCC) from a day's milk is the best indicator of the extent to which the gland is involved in fighting a mastitis infection. The DHI program provides a monthly SCC which identifies those cows with subclinical mastitis. The DHI SCC is highly correlated to losses in milk yield. The DHI SCC program assists dairy farmers in monitoring herd subclinical mastitis status, progress in mastitis control programs such as milking practices or equipment, cow environment and dry cow therapy, and can be used in making decisions regarding cow segregation and culling.
May 1, 2009 404-228
Dairy Crossbreeding Research: Results from Current Projects

Many dairy producers practice some crossbreeding, and the numbers increase every year. Motivating factors include a desire to improve fertility, survival, milk components, and calving ease. Some producers want cows smaller than mature Holsteins. Several large, long-term dairy crossbreeding experiments have been conducted in the United States in the past. Cows involved in previous projects were not the result of intensive selection programs for type and production that produced today’s purebred populations.

May 1, 2009 404-094
Dairy Crossbreeding: Why and How

The Merit indexes are dairy sire selection tools published by USDA that combine genetic evaluations for production, health, fitness, and fertility traits. The indexes are designed to improve the lifetime economic performance of future dairy cows. Periodic revisions include new traits and adjusted economic weights. This document describes the indexes as revised for August 2006. Future changes are inevitable, thus the title “2006 Version.” 

May 1, 2009 404-093
Dairy Heifer Health, Disease Control, and Vaccinations

The future of the dairy herd is dependent on the production of superior heifers to replace culled lactating animals. Therefore, it is imperative that the health status of the replacement animal is optimized to present a healthy first calf heifer to the lactating herd. Studies have consistently demonstrated the detrimental effects of pneumonia in calves on age at first calving and on milk production once these animals enter lactation. Calves with respiratory infections were twice as likely to leave the herd and age at first calving was delayed by 6 months when compared with calves that did not experience respiratory disease or pneumonia. In another study, calves treated for scours were three times more likely to calve at 30 months of age or greater.

May 1, 2009 404-284
Dairy Overview Of The 2014 Farm Bill Feb 27, 2014
Dairy Pipeline, April 2014 Mar 26, 2014 DASC-36NP
Dairy Pipeline, January/February 2014 Jan 7, 2014 DASC-31NP
Dairy Pipeline, January/February 2015 Jan 7, 2015 DASC-45NP
Dairy Pipeline, July/August 2013 Jul 1, 2013 DASC-24NP
Dairy Pipeline, July/August 2014 Jun 30, 2014 DASC-40NP
Dairy Pipeline, June 2014 May 23, 2014 DASC-38NP
Dairy Pipeline, March 2014 Feb 27, 2014 DASC-35NP
Dairy Pipeline, March 2015 Mar 2, 2015 DASC-47NP
Dairy Pipeline, May 2014 Apr 24, 2014 DASC-37NP
Dairy Pipeline, November/December 2013 Oct 24, 2013 DASC-29NP
Dairy Pipeline, November/December 2014 Nov 4, 2014 DASC-43NP
Dairy Pipeline, October 2013 Sep 25, 2013 DASC-28NP
Dairy Pipeline, October 2014 Sep 30, 2014 DASC-42NP
Dairy Pipeline, September 2013 Sep 5, 2013 DASC-26NP
Dairy Pipeline, September 2014 Aug 25, 2014 DASC-41NP
Dairy Pipeline: Activities Mar 2, 2015
Dairy Pipeline: Activities Jan 7, 2015
Dairy Pipeline: Activities Nov 4, 2014
Dairy Pipeline: Activities Sep 30, 2014
Dairy Pipeline: Activities Aug 25, 2014
Dairy Pipeline: Activities Jun 30, 2014
Dairy Pipeline: Activities May 23, 2014
Dairy Pipeline: Activities Apr 24, 2014
Dairy Pipeline: Activities Mar 26, 2014
Dairy Pipeline: Activities Feb 27, 2014
Dairy Pipeline: Activities Jan 7, 2014
Dairy Pipeline: Activities Oct 24, 2013
Dairy Pipeline: Activities Sep 25, 2013
Dairy Pipeline: Activities Sep 5, 2013
Dairy Pipeline: Activities Jul 1, 2013
Dairy Producer Input Sought Regarding Genomics Sep 25, 2013
Dairy Producer Input Sought Regarding Genomics Sep 5, 2013
Decisions Determine Your Farm's Direction Oct 24, 2013
Distiller's Grains for Dairy Cattle and Potential Environmental Impact

Ethanol is produced when starch in corn grain is fermented. Most other constituents in the grain remain unchanged. The end product of the corn is distiller’s grains or DDGS (distiller’s grains with solubles). The DDGS retain the original fatty acids, protein, and phosphorus. In addition, variability in the grain nutrient content used in the fermentation process and the actual process itself results in a feed with variable nutrient content. Distiller’s grains can be fed either in the wet (less than 25 percent dry matter) or dry (greater than 85 percent dry matter) form. Wet DDGS are difficult to store and must be fed within a few days of production. The wet DDGS can be the most cost-effective, however, if used close to where they are produced.

May 1, 2009 404-135
Dr. Gonzalo Ferreira Joins Virginia Tech Dairy Science Sep 5, 2013
Early Heifer Development and Colostrum Management

Raising dairy replacement heifers is expensive. In fact, if the dairy is divided into different enterprises (eg. labor, feed cost for lactating cows, facilities, etc.), rearing replacements is the second largest cost, behind feed cost for lactating cows. The percentage will vary from farm to farm, but approximately 9% to 20% of the expenses incurred will involve rearing and developing heifers. Therefore, heifers should represent a sound investment, as their impact on future herd profitability is enormous.

May 1, 2009 404-282
Environmental Streptococcal and Coliform Mastitis

Well managed dairy herds with low somatic cell counts (SCC below 200-300,000) often may experience problems with onsets of clinical mastitis. Approximately 40-45% of the mastitis cases in low SCC herds are caused by environmental pathogens which can be difficult to detect because of their short duration. Cows in low SCC herds are most susceptible to environmental streptococci and coliform infections after drying off and just prior to calving but which appear in early lactation.

May 1, 2009 404-234
Environmental Streptococci and Enterococcus spp.: A Practical Summary for Controlling Mastitis Jul 12, 2012 DASC-7P
Escherichia coli: A Practical Summary for Controlling Mastitis Jul 29, 2011 404-224
Feeding Protein to Meet Dairy Cow Nutrient Requirements Can Result in Cheaper, Environmentally Friendly Rations

Animal agriculture is facing the significant issue of managing excreted nutrients, and researchers are designing programs to address the issue. The intense management of animals in the poultry, swine, and dairy industries can contribute to environmental pollution. Although there are more beef than dairy cattle in Virginia, beef cattle are typically maintained on pasture and dispersed over a greater area. Feed management in dairy cows to reduce nutrient consumption has been identified as being very effective in reducing output of potentially polluting nutrients such as nitrogen and phosphorus.

May 1, 2009 404-354
Five Simple Tips To Reduce The Negative Impacts Of Hot Weather On Diary Cattle Jul 1, 2013
Genetic Improvement Using Young Sires With Genomic Evaluations Apr 21, 2010 404-090
Group Housing For Calves: Is This The Right System For You? Nov 4, 2014
Guidelines to Culling Cows with Mastitis

With the price of milk and the cost of milk production where they have been the past few years, tight control over dairy management decisions will make a significant impact upon farm returns. One decision which will improve profitability is to cull problem cows. A dairy farm's goals should include: (1) Maintaining profitable levels of milk production based upon sound feeding, breeding, and management programs; and (2) An effective herd health program to reduce losses from mastitis and other cow disorders. On most dairy farms, annual culling rates exceed 30-35% of the herd. According to December 1998 DHI summary for Virginia, 36% of all cows enrolled in Virginia's DHI program were culled. 

May 1, 2009 404-204
Handling a Herd Mastitis Problem

A herd whose bulk tank somatic cell count exceeds 200,000 or DHI SCC score is above 2.5-3.0, or a herd where more than 3 cows per 100 cows show clinical mastitis over a month's time has a costly mastitis problem because of significant lost milk production and reduced economic returns. Herds with elevated SCC may not have many cows that are clinical, but subclinical mastitis infections may cause permanent destruction of milk secretory cells with permanently lower milk producing ability. In other herds, short duration environmental infections may not have great impact upon SCC, but these cows also have depressed milk yields, and considerable milk may be discarded because of antibiotic treatments. Consequently, dairy herds are losing money through greater culling, increased labor intensity, and greater risk of shipping milk that may be contaminated with antibiotic residues.

May 1, 2009 404-238
How Does Milk Quality In Virginia Measure Up? Mar 26, 2014
How Good Is The Reproduction In Your Herd? Apr 24, 2014
How Soon After Calving Are Your Cows Being Bred? Sep 25, 2013
How to Make an Adjustable Rope Halter and Tie Useful Knots Oct 29, 2009 404-280
If You Don't Measure It You Can't Manage It! Jun 30, 2014

The mating of related individuals is called inbreeding. New dairy animals created by AI or natural service inherit a random sampling of the genetic makeup of each parent. If the parents are related, some of the genes transmitted to offspring by each parent will be copies of the same genes found in the common ancestor(s) which caused the parents to be related. As the genetic relationship between parents increases, the likelihood that pairs of genes in offspring are copies of a single gene in an ancestor generations back increases. Such genes are said to be "identical by descent."

May 1, 2009 404-080
Inspiring Youth and Families to a Future in Agriculture Aug 25, 2014
Is Your Silo Ready For Harvest? Sep 5, 2013
It Has Got To Be Clean! Mar 26, 2014
It's Not About The Crop...It's About The Crop Rotation Sep 30, 2014
Klebsiella spp.: A Practical Summary for Controlling Mastitis Jul 29, 2011 404-223
Limit These Feeds in Rations for Dairy Cattle

When feeding lactating dairy cows it is best to limit amounts of certain feeds. Reasons can be problems with palatability, high oil or fat content, and imbalances of certain nutrients. Knowing these restrictions can prevent problems from occurring. Also, combinations of some of these feeds can be a problem if the maximums are used with no regard to type and amount of nutrients that are provided. This is where your nutritionist can be an asset in identifying optimal relationships with consideration for cost of the ration. Here is a list of some feeds used in Virginia and suggested maximums. Remember that these are maximum amounts and not necessarily optimum amounts.

May 1, 2009 404-119
Making Dairy Information Systems Work Sep 25, 2013
Milk Quality In The Southeast - How Did Virginia Measure Up In 2013? Nov 4, 2014
Nuisance Bird Control Jan 7, 2015
Nutrition For The Early Developing Heifer

Several factors can dramatically reduce replacement-rearing cost and increase potential profits for the producer: (1) maximizing immunity from colostrum to minimize mortality and sickness, (2) formulating rations for specific weight gains during strategic periods of development and avoiding over-fattening prior to puberty because it impairs mammary development, (3) formulating rations for an average daily gain of 1.8 lb. for Holstein heifers, (4) using AI sires ranking in the top 20% for (PTA$) to optimize genetic improvement, (5) monitoring age, body weight, wither height, body condition score as well as peak milk and ME milk yield of first lactation heifers to evaluate management at first calving, and (5) controlling the size of the replacement herd by calving heifers at 24 months and raising no more than needed.

May 1, 2009 404-283
On-farm Tests for Drug Residues in Milk

The presence of drug or antibiotic residues in milk and meat is illegal. Milk supplies containing detectable concentrations are not acceptable. Unless drug residues are avoided to protect milk's reputation as a healthy, safe food, the market becomes jeopardized. Consumers want to be confident that their food supply is free of contamination by herbicides, pesticides, drugs, or antibiotics. Approximately 5-10 percent of the population is hypersensitive to penicillin or other antibiotics and suffers allergic reactions (skin rashes, hives, asthma, anaphylactic shock) at concentrations as low as 1 ppb penicillin. There is concern that small amounts of certain antimicrobial agents may significantly shift the resistance patterns in the microbial population in the human intestinal tract.

May 1, 2009 404-401
Paying Attention to Dietary Cation-Anion Balance Can Mean More Milk and Fewer Metabolic Problems

Nitrogen (N) and phosphorus (P) are the two nutrients that cause the most concern with respect to environmental pollution from animal manure. Generally, higher concentrations of N and P in the ration result in their greater excretion in urine (N) and feces (N and P). Overfeeding these nutrients can be a significant problem, particularly if nutrient levels accumulate in the soil and contaminate water sources through leaching or surface runoff. Nitrogen can also volatilize as ammonia and pose a potential environmental problem with air emission standards, which are currently under review. 

May 1, 2009 404-131
Preventing Drug Residues In Milk and Cull Dairy Cows

Preventing drug contamination of milk and meat is the responsibility of every farm. Drug residues can be avoided by a well planned drug use program. There is no way that a milk plant can use contaminated milk. The sale of contaminated milk or meat will cause the responsible party to be subjected to severe penalties, including suspension of permits and monetary loss. Milk with drugs can adulterate a whole truckload or holding tank of milk.

May 1, 2009 404-403
Proper Dry Cow Management Critical for Mastitis Control

According to the National Mastitis Council, using FDA-approved intramammary antibiotics at drying off can decrease the number of existing mastitis infections and prevent new infections during the early weeks of the dry period. Dry cow therapy has the following advantages over lactation therapy: a) The cure rate is higher than that achieved by treatment during lactation, b) A much higher dose of antibiotic can be used safely, c) Retention time of the antibiotic in the udder is longer, d) The incidence of new infections during the dry period is reduced, 

May 1, 2009 404-212
Protect Your Calves' Health With Biosecurity Protocols Mar 2, 2015
Reference Guide for Mastitis-Causing Bacteria Jun 10, 2010 404-230
Risks and Hazards of Manure Management May 23, 2014
Serratia spp.: A Practical Summary for Controlling Mastitis Jul 29, 2011 404-225
Should Winter Crops Be Considered Cover Crops In Dairy Farming Systems? Mar 2, 2015
Silage Density Sep 5, 2013
Silage Shrinkage: What Does The Data Say? Feb 27, 2014
Silo Management, Learning From The Experts Jul 9, 2014 DASC-39NP
Sire Evaluations for Health and Fitness Traits

Dairy producers have selected for higher milk production for many years. Genetic improvement causes an average Holstein cow born in 2003 to produce over 7,000 pounds more milk in one lactation than her ancestor born in 1960 produced. Type traits, particularly udders and feet and legs, have also improved because of intensive selection. However, the health and fertility of dairy cows cannot be included among these success stories. Genetic trend was responsible for half of a 9-point decline in pregnancy rate in Holsteins between 1960 and its low point in 1995. Dairy-cattle breeders responded by developing national genetic evaluation programs for a number of fitness traits in recent years. 

May 1, 2009 404-087
Staphylococcus aureus Mastitis: Cause, Detection, and Control

Staphylococcus aureus (S. aureus) mastitis is extremely difficult to control by treatment alone. To date, successful control is gained only through prevention of new infections and culling of infected animals. S. aureus organisms colonize teat ends and/or teat lesions. Spread of infection can occur through milkers’ hands, washcloths, teat cup liners, and flies. During milking, irregular vacuum fluctuations can force bacteria up into the teat canal, leading to the potential for new infection. If not culled, infected cows must be segregated from the milking herd and milked last, or milked with separate milking units. A backflush system may help reduce bacterial numbers within the liners, but rinsing units by hand is certainly not recommended.

Jun 11, 2010 404-229
Staphylococcus aureus: A Practical Summary for Controlling Mastitis Jul 29, 2011 404-226
Strategies For Extra Dairy Profits Sep 30, 2014
Strategies to Reduce Amounts of Nitrogen and Phosphorus in Dairy Rations

Nitrogen (N) and phosphorus (P) are the two nutrients that cause the most concern with respect to environmental pollution from animal manure. Generally, higher concentrations of N and P in the ration result in their greater excretion in urine (N) and feces (N and P). Overfeeding these nutrients can be a significant problem, particularly if nutrient levels accumulate in the soil and contaminate water sources through leaching or surface runoff. Nitrogen can also volatilize as ammonia and pose a potential environmental problem with air emission standards, which are currently under review. 

May 1, 2009 404-130
Streptococcus agalactiae: A Practical Summary for Controlling Mastitis Jul 19, 2012 DASC-6P
Streptococcus dysgalactiae: A Practical Summary for Controlling Mastitis Jul 12, 2012 DASC-5P
Streptococcus uberis: A Practical Summary for Controlling Mastitis Jul 12, 2012 DASC-8P
Summer Fly Control May 23, 2014
Temperatures Are Rising - Make Sure Your SCC Doesn't Follow Jul 1, 2013
Testing Bulk Tank Milk Samples

Samples of bulk tank milk are collected regularly and milk quality tests are performed by milk coops, plants, or Virginia Department of Agriculture and Consumer Services. Some milk coops offer bulk tank profiles which involve several tests related to milk quality. The various tests are briefly described below, as well as a list of goals for high quality milk and conditions which adversely affect test results. Hopefully, an explanation of the use of these tests will help Virginia dairy farmers produce high quality milk, which has been defined by the Extension Milk Quality Leadership Council as milk with:

May 1, 2009 404-405
Tests Available for Measuring Forage Quality

Forage quality has typically been determined by measuring the dry matter, crude protein, fiber, and estimated energy content. Forage testing labs are now able to estimate the actual digestibility of feeds by using newly available tests.

May 1, 2009 404-124
The All-Breed Animal Model
The all-breed animal model is the genetic-evaluation system used to evaluate dairy animals in the United States. Scientists and technicians at the Animal Improvement Programs Laboratory (AIPL) at Agriculture Research Service in Beltsville, Md., developed and support the system. There are two major differences between the all-breed animal model and the single-breed animal model it replaced:
  1. Accurate genetic evaluations of animals with relatives in more than one breed are now possible.
  2. Animals of different breeds within the same herd are now used together for contemporary comparisons.
May 1, 2009 404-086
The Basics of Forage Testing

In order to have an accurate forage test for ration formulation, it is important to have a representative sample. The method of sampling varies with forage type. Silages (corn or hay crop) can be sampled either at harvest or at feed out. There is a slight reduction in dry matter and increase in fi ber during storage, but it is possible to use the analysis of the fresh material to indicate the quality after ensiling. If sampling fresh material at harvest, it is best to take three to four handfuls from every third load or more and place them in a container with all samples from the same field. Keep it covered to prevent drying. After mixing the composite, a sub-sample can be taken for analysis (only a pint or 100 grams is needed).

May 1, 2009 404-300
The Merit Indexes - 2006

The Merit indexes are dairy sire selection tools published by USDA that combine genetic evaluations for production, health, fitness, and fertility traits. The indexes are designed to improve the lifetime economic performance of future dairy cows. Periodic revisions include new traits and adjusted economic weights. This document describes the indexes as revised for August 2006. Future changes are inevitable, thus the title “2006 Version.” 

May 1, 2009 404-088
The Role of Milking Equipment in Mastitis

The goal for any dairy farm should be to deliver a high quality product that has consumer appeal. The objective of any heards milk management program should include: (1) maximise yield secreted by the mamary gland, (b) milk cows out in a short peroid of time, (c) prevent damage to teats, teat ends, and the udder, and (d) have no adverse effect on chemical composition of milk. It must be recognized that factors other than milking equipment, such as milking practices, can influence milking performance and quality.

May 1, 2009 404-742
Understanding the Basics of Mastitis
Mastitis occurs when the udder becomes inflammed because leukocytes are released into the mammary gland in response to invasion of the teat canal, usually by bacteria. These bacteria multiply and produce toxins that cause injury to milk secreting tissue and various ducts throughout the mammary gland. Elevated leukocytes, or somatic cells, cause a reduction in milk production and alter milk composition. These changes in turn adversely affect quality and quantity of dairy products.
May 1, 2009 404-233
Using DHI records to make culling decisions: Lactation Ratings, ERPA's, and Predicted Producing Abilities

Culling decisions affect the profitability of the dairy herd. Feed resources and management skills used to maintain unproductive cows would generate more income if applied to productive cows. DHI records contain important information to help guide culling decisions. This guideline describes three systems for rating cows for production traits. Producers recognize that information about production must be combined with reproductive and health status, age, and other factors to make profitable culling decisions. Suggestions for combining information to make good culling decisions are offered.

May 1, 2009 404-083
Using Heritability for Genetic Improvement

Concepts surrounding the word "Heritability" (frequently represented by the symbol h2) are among the most important that a breeder of dairy cattle should understand. Heritability applies to a single trait measured on animals in a specific population at a given point in time. Estimates of heritability for a trait can differ between breeds of dairy cattle and may change slowly over time. Heritability is estimated from performance records on animals and pedigree information used to establish genetic relationships between those animals. Heritability helps explain the degree to which genes control expression of a trait. Heritability is used to calculate genetic evaluations, to predict response to selection, and to help producers decide if it is more efficient to improve traits through management or through selection. This guideline highlights definitions and uses of heritability and lists estimates of heritability for several important traits in dairy cattle breeding.

May 1, 2009 404-084
VCE and the Dairy Science Department Welcome Jeremy Daubert and His Family to Virginia Jan 7, 2014
Virginia 4-H Beef Heifer Project Junior Record Book Jun 27, 2013 4H-140P
Virginia 4-H Beef Heifer Project Senior Record Book Jul 1, 2013 4H-141P
Virginia 4-H Horse Project Junior Record Book May 1, 2009 406-122
Virginia 4-H Horse Project Senior Record Book May 1, 2009 406-123
Virginia 4-H Market Beef Project Junior Record Book Aug 23, 2013 4H-142P
Virginia 4-H Market Beef Project Senior Record Book Aug 27, 2013 4H-143P
Virginia State Feed Association & The Virginia Tech Nutrition "Cow College" Oct 24, 2013
Your Herd's Reproductive Status
Maintaining a high level of reproductive efficiency is required if dairy herd profitability is to be maximized. Reproductive performance of a dairy herd is a function of certain management policies and how well these management policies are implemented in the day-to-day management of the herd.

The first step in evaluating the reproductive performance is to identify key measurements and use them as guides in developing or altering herd management policies and practices. The calving interval should be the starting point in evaluation of prior herd performance. For maximum production, a calving interval of 12.3 to 12.8 months must be achieved. When calving intervals vary beyond this range, milk production drops significantly, with a sharp drop when calving intervals exceed 13.6 months. 

May 1, 2009 404-005