Have You Had Your Feed Tested?

This is a guest post written by John McKinnon, Ph.D. at the University of Saskatchewan.

As a nutritionist, feed testing is a fundamental tool that I rely on to assist beef producers with their feeding programs. This is true whether I am dealing with feedlots or cow-calf operations. Accurate knowledge of feed quality, particularly the operation’s forage base allows one to develop feeding strategies for specific production scenarios and minimize the over- or under-feeding of nutrients. By so doing, one is able to achieve desired production targets and save on supplemental feed costs.

While feed testing seems like a “no brainer”, it is surprising how many cattlemen skip this critical management tool. It seems many would rather rely on visual appraisal (i.e. colour, plant species, and leaf content) or knowledge of cutting time to judge quality. While these are all indicators of forage quality, they do not substitute for a feed test particularly when it comes to the energy and protein content of that forage. For example, the protein content of brome hay can range from as low as 5 to 6% up to 18% depending on stage of maturity at cutting. While visual appraisal may help separate the good from the poor quality hay, it is not going to help you decide how much protein supplement, if any, you need to background calves when feeding this hay. Only a feed test can accurately help you make this decision.

With respect to energy content, a feed test will give you values as total digestible nutrients (% dry matter) or as digestible energy (Mcal/kg dry matter) and depending on the laboratory used for testing,  you may also get net energy values for maintenance and gain (Mcal/kg dry matter). These energy values can be used to determine the amount of forage allotted in bale or swath grazing situations or can help you determine how much grain you need to supplement when backgrounding calves.

The feeding value of a given forage is often based on its fibre content. A feed test can generate two fibre values that reflect either its relative energy content or feeding value. These include acid (ADF) and neutral detergent (NDF) fibre. High ADF values indicate that the hay was cut at a late stage of maturity and as a result it will be poorly digested by the cow. This late cut hay will be lower in energy content than the same hay cut at an earlier stage of maturity with a lower ADF value. High NDF levels also indicate a more mature forage at harvest and more importantly is indicative of the degree to which cattle will consume the feed – high NDF values limit forage intake!  Again, visual appraisal will not help you accurately identify the energy content nor the feeding value of your hay.

As indicated above, accurate knowledge of the energy and protein content of your feed can allow you to target economic feeding strategies for various classes of cattle. For example, when feeding the pregnant beef cow, a basic principle is to adjust your feeding program to match her requirements as she moves through the second and third trimesters of pregnancy with the appropriate quality and quantity of feed and to do so in a cost effective manner.

Pregnancy requirements, particularly for nutrients such as energy and protein, increase dramatically in the last 6 to 8 weeks prior to calving.  This concept is illustrated in Table 1 below for both a mature cow as well as for a bred heifer.  Note that for the mature cow, energy requirements at the end of the third trimester are 20% higher than 2^nd trimester requirements.  This is true whether you use total digestible nutrients (TDN) or net energy for maintenance as an energy reference. The increase is even higher for the bred heifer, as she not only needs to meet requirements for pregnancy but also has to continue to grow to mature weight.  With respect to nutrients such as protein, calcium and phosphorus, similar increases are evident for both animals as pregnancy advances.

Meeting these increased nutritional needs by feeding a balanced ration is critical to maintaining a normal pregnancy and to prevent weight loss. It will also influence the success of your subsequent breeding program. Inadequate nutrition will cause cows to lose weight and body condition. This is true regardless if the issue is feed quality or quantity. Cows that lose weight during the last trimester or from the period from calving through breeding are subject to calving difficulties, extended periods of anestrous and/or poor first service conception rates. The result will be an extended breeding season and/or an increase in the number of open cows. As well, next year’s calf crop can be affected not only due to lower numbers but also as a result of reduced weaning weights due to the fact that more calves are likely to be born late in the calving season.

Having your forage tested is the first step to ensuring that you are meeting the requirements of your cows for maintenance and pregnancy.  Today’s feed test laboratories use both wet chemistry and near infrared spectrometry to offer accurate results and rapid turn-around times. A basic forage analysis will provide you with moisture , energy (i.e. total digestible nutrients, digestible energy and/or net energy content) and crude protein values as well as a mineral package (calcium and phosphorus). More advanced packages can provide you with details on all macro and trace minerals, acid and neutral detergent fibre content, nature of protein (soluble, degradable, bypass, heat damaged), fat content, nitrate and other potential toxins. This information can be used by you and your nutritionist to develop feeding programs that meet the requirements of pregnant, wintering beef cows and replacement heifers, as well as for targeting gains of growing cattle! At $25 to $30 a sample for a basic feed test, it truly is a no brainer! So again I ask the question – Have you tested your feed this winter?

Table 1.  Nutrient requirements for pregnancy for a mature 1300 pound cow and 900 bred heifer. Values were generated using Alberta Agriculture’s Cow-Bytes Program. (Assumptions include breeding in late August for June 1 calving, typical Canadian winters, access to shelter from wind and a daily gain of 1.25 pounds for the bred heifer in addition to weight gain from pregnancy.)

Learn More

• Video: Importance of Feed Testing and How to Obtain a Proper Sample – Saskatchewan Ministry of Agriculture
• Nutrient Testing – Ontario Ministry of Agriculture and Rural Development
  Includes a list of feed analysis laboratories in Ontario.
• CowBytes Ration-Balancing Software – Alberta Agriculture and Rural Development
• Video: Beef Research School: Using a Feed Test to Maximize Profits & Avoid Pitfalls – RealAgriculture.com

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• Cattle Nutrition
• Feed Rations
• Feed Testing
• John McKinnon Ph.D.
• Pregnancy