Introduction

PCBFA encourages producers to test their forage feed samples for quality in a laboratory. Forage analysis includes determining crude protein (protein), total digestible nutrients (a measure of energy), minerals (macro, trace or both) and detergent fibres. PCBFA facilitates feed testing of samples sent in by producers, interpretation of the laboratory results and assisting producers of the Peace Country region to formulate rations for different categories of beef cattle. These efforts give producers a chance to assess their feed inventory (e.g. hay, greenfeed, silage) and have a good feeding plan in place for their cattle.  Knowing the nutrient content of the feed resources on farms and comparing them with the animal's nutrient requirements enables a producer to see if supplements are needed to improve animal performance or health. Livestock are most productive when fed a ration balanced according to their nutrient needs and producers will not know if the rations meet the nutrient requirements of their livestock if they do not regularly send feed samples to the lab for analyses. This report provides a summary of the 2022 feed types (different forage-type feeds and grains) submitted by producers for feed testing from different parts of the Peace Region, particularly within the various municipalities that PCBFA serves. The results are discussed in relation to the nutrient requirements of beef cattle stock.

Methods

From spring to fall 2022, a total of 158 feed samples from producers were analyzed for feed quality at the Central Testing Laboratory in Winnipeg, Manitoba using standard laboratory procedures for wet chemistry and/or near-infrared reflectance (NIRS) spectroscopy. For this report, the feed types have been organized into 25 groups as submitted by producers with minor adjustments made to reflect main feed types (Table 1). The results are presented and discussed in relation to feed types meeting the minimum daily nutrient requirements for crude protein, total digestible nutrients (energy), calcium (Ca), phosphorous (P), magnesium (Mg), potassium (K) and micro minerals (Cu – copper; Mn – manganese; Fe – iron) of dry, mid-gestating beef cows (low nutrient requirement) and finishing beef calves (high nutrient requirement) as recommended by the National Academies of Sciences, Engineering and Medicine (NASEM, 2016). In addition, the data for each feed type was analyzed and where possible, sums, means, percentages/frequencies and modal values were calculated.

Results

Categories of Feed Samples - The bulk of samples (60%) consisted of alfalfa grass hay mixes, hay-unspecified, hay-grass and alfalfa-hay coming in that order (Figure 1). Silages came in second (18%) as one of the main feed type groups sent in by producers for analysis and were composed of mixed silages and various cereal (wheat, barley and oat) silages. The remaining feed types were made up of greenfeed (6.5%), grains (6%) and other minor feed types such as standing corn (4%) and straws (3%). 

Protein – The crude protein (CP) content of forage ranged from 3.6% to 19.8%. Among the different straws (barley, oat, and canola), canola screenings had the highest protein content (19.8% CP), followed by wheat screenings (16.9% CP) (Table 2). The silages, including alfalfa grass silage and clover silage, had appreciable protein ranging from 9.5% to 15.2%. Protein serves as a building block. According to the Beef Cow Rule of Thumb (Table 3), the protein requirements for an average mature beef cattle are 7%, 9%, and 11% CP in mid-pregnancy, late pregnancy, and after calving, respectively. If the diet of beef cattle has less than 7% protein, the fermentation process of feedstuff in the rumen by microbes will not function properly, leading to high levels of undigested fibre in the manure. The Feeder Calf Rule of Thumb suggests that feeder calves weighing between 550 and 800 lbs require a ration with 14% CP, those weighing between 800 and 1,050 lbs need 12% CP, and those weighing 1,050 lbs to the finishing stage need 10% CP. Based on these two rules and referring to Table 1, it is evident that most feed types, except for straws and standing corn, meet the nutritional requirements of a dry mid-gestating beef cow. However, the same is not true for the protein requirements of finishing calves. The feed types listed in Table 1 do not meet the 12-14% CP necessary for growing and finishing calves during backgrounding. Hence, additional protein supplementation, such as leguminous forage, is required for all feed types except grains and some silages, to meet the needs of growing calves.

Energy – The total digestible nutrients (TDN), commonly referred to as energy, are important for beef cow rations that primarily consist of forage. It serves as a good indicator of the energy content provided by a feed. The rule of thumb for energy is 55-60-65 (Table 3). This means that a mature beef cow needs a TDN energy reading of 55% in mid-pregnancy, 60% in late pregnancy, and 65% after calving (nursing beef cows) to maintain a body condition score (BCS) throughout winter. The energy content of the feeds in this study ranged from 37.7% to 79% (Table 1). From Table 2, it is evident that all the straws, about one-tenth of the mixed alfalfa grass hay-mixed, and half of the hay-grass feed types will not meet the energy requirements of a dry beef cow. Most feed types (except for grains) will also fall short in meeting the energy requirements of growing and finishing calves, which need 65-70% TDN. Only wheat silage and cocktail greenfeed met the 65-70% TDN requirement for weaned calves. Among the feeds, wheat screening had the highest TDN content (86% TDN), followed by oat grain (77% TDN).

Minerals – The mineral contents of the tested feeds varied as follows (Table 1):

Calcium (Ca) – Ranging from 0.07% for oat grain to 1.94% for alfalfa silage.

Phosphorus (P) – Ranging from 0.13% for alfalfa grass to 0.47% for canola screenings.

Magnesium (Mg) – Ranging from 0.12% for barley straw, greenfeed-unspecified, haylage, and oat grain to 0.31% for canola screenings.

Potassium (K) – Ranging from 0.5% for canola straw, oat grain, and wheat screenings to 2.1% for oat straw and corn standing.

Based on Table 2, almost all feed types met the calcium requirements for gestating dry cows. However, deficiencies were noted for most feeds in meeting the calcium requirements for finishing calves (0.57%). Barley silage and straw, corn standing, over half of the hay-grass feed type, and all the hay-unspecified and grain products were deficient in meeting the calcium requirements for finishing calves. The situation for phosphorus is similar to calcium, with deficiencies observed in most hay feed types and all oat grain and straw feeds for dry cows. From Table 1, it is evident that almost all feed types (except for some grains) provided less than 0.3% of the phosphorus needed daily by growing calves. For magnesium and potassium, most feed types contained adequate amounts to meet the requirements for both dry gestating cows and growing calves. The analysis of trace minerals in most feed samples (data not provided) indicated deficiencies in meeting the minimum copper requirements of 10 ppm (Table 3).

Implications and Recommendations

• Most feed types, except for straws and standing corn, can meet the protein requirements for dry cows but not for finishing calves. Supplementation with high protein feed types, such as leguminous forages (e.g., alfalfa or alfalfa-dominated hay), is recommended.

• The TDN content was generally low for straws and far below the requirements of a dry gestating beef cow. Additionally, most feed types were found to be deficient in TDN for finishing calves. Producers feeding these feed types will need to supplement with additional energy sources to compensate for the energy shortfall in the diets of growing and finishing calves.

• The Ca and P requirements for finishing calves were not met by most feed types. Producers should consider providing custom mineral supplements to compensate for these deficiencies. Brassicas are a rich source of Ca and P and can be included in diets to make up for these shortfalls.

• Producers should provide mineral supplementation to ensure that all beef cattle have sufficient minerals in their diets. Previous studies have reported copper deficiencies in most forages grown in the Peace Region. Producers are encouraged to request micro-mineral analysis when submitting forage samples to the lab.

• Nitrates were not specifically analyzed in this study, likely because the year had near-normal weather conditions with no extreme events that could lead to nitrate accumulation in forages, such as hail and drought. However, producers are advised to request nitrate analysis if they have any concerns.

• It is recommended that producers harvest forages at the appropriate stage (see Table 4 for annual forage crops) to optimize both yield and quality. Proper storage practices should also be followed to prevent deterioration in forage quality.

References

NASEM (National Academies of Sciences, Engineering, and Medicine). 2016. Nutrient requirements of beef cattle. 8th revised edition. The National Academies Press, Washington, DC. doi:10.17226/19014.