Wheat middlings and related milling by-products are useful sources of energy and protein for ruminants. They can replace part of the cereal grain in balanced diets and provide supplements for forage-based feeding systems. Their feeding value depends on the proportions of flour, germ and fibrous tissues remaining after milling. Although middlings supply fermentable fibre, their small particle size limits its physical effectiveness, so their fibre cannot be considered equivalent to that of long forage (NASEM, 2021).
The protein and residual starch in middlings are readily available to rumen microorganisms: in an in situ comparison of eight feeds using three cannulated dairy cows, middlings had the highest estimated ruminal availability of both crude protein and starch. These measurements help explain the need to balance middlings with the other sources of fermentable energy and protein in the ration (Batajoo et al., 1998).
Inclusion rates
Published guidance and successful experimental inclusion levels are summarised below. Percentages refer to total diet dry matter (DM) unless another basis is specified. The sheep experiments tested particular durum-wheat middlings in balanced pelleted complete diets (Tufarelli et al., 2011a; Tufarelli et al., 2011b). Differences in starch and fibre content between milling products also limit the transfer of these results to other products, particularly starch-rich feed flour (NASEM, 2021).
| Animal or feeding system |
Inclusion or allowance |
Basis and qualification |
| Lactating dairy cows |
15–25% of total ration DM |
Published upper inclusion range, intended to prevent palatability problems; the guide also expresses this as 25–50% of the grain mix (Amaral-Phillips et al., 2006). |
| Lactating dairy cows: pelleted concentrate |
Up to 40% of the concentrate mixture |
Milk yield was maintained at this level, whereas 60% reduced yield despite unchanged intake. The concentrate made up about 60% of the ration; middlings percentages in its formulation were expressed as fed (Acedo et al., 1987). |
| Lactating dairy cows: partial forage replacement |
15–17% of total diet DM |
Levels tested when replacing part of the maize silage or alfalfa contribution. Milk production was maintained or increased, but middlings fibre was less effective than forage fibre in stimulating rumination or supporting milk fat (Wagner et al., 1993; Depies et al., 1995). |
| Beef cattle |
No more than 50% of total diet DM |
Broad extension ceiling. Middlings should be combined with other ingredients because they ferment readily (Parish et al., 2021). |
| Growing and finishing beef cattle |
About 35.5% of total diet DM in growing diets; 35% and 50% in finishing diets |
Levels tested without significant changes in growth or feed efficiency; carcass traits were also unaffected in finishing steers. Ruminal pH was lower in a companion experiment with the 50% diet (ZoBell et al., 2003). |
| Lactating ewes |
50% of total diet DM |
Successfully tested in a balanced pelleted total mixed ration; milk yield was maintained. (Tufarelli et al., 2011a). |
| Fattening lambs |
60% of total diet DM |
Successfully tested for 50 days in a balanced pelleted total mixed ration (Tufarelli et al., 2011b). |
| Goats receiving forage |
Up to 1% of body weight daily as a supplement |
Published guidance for grazing goats; the guide does not specify the moisture basis (Gurung, 2013). A meat-goat trial tested 1% of body weight daily as fed, with hay available freely and the mineral balance corrected (Moore et al., 2002). |
Dairy cattle
Middlings can help formulate dairy diets containing less cereal starch while supplying energy and rumen-degradable protein, but their fibre is less physically effective than forage fibre (NASEM, 2021). Their low calcium and high phosphorus contents require an appropriate mineral balance (Amaral-Phillips et al., 2006).
Two trials, each with 18 lactating cows, compared pelleted concentrates containing up to 40% or 60% middlings, replacing maize, sorghum grain and cottonseed meal. Concentrate supplied about 60% of the ration, with alfalfa hay providing the remainder. Milk yield was maintained with 20% or 40% middlings in the concentrate, but decreased at 60%; intake and milk fat percentage were unchanged. Thus, satisfactory intake of a high-middlings pellet did not necessarily indicate that it would maintain milk production (Acedo et al., 1987).
In a trial with 12 lactating Holstein cows, increasing middlings from 6.8 to 13.4% of diet DM, together with beet pulp and other formulation changes, reduced dietary starch from 24.6 to 17.7%. Feed intake, solids-corrected milk yield and feed efficiency were maintained, averaging 26.5 kg DM/day, 40.8 kg milk/day and 1.54 kg milk/kg DM, respectively. Ruminal pH and chewing activity were also unchanged, although organic matter digestibility was lower on the lower-starch diets (Dann et al., 2014).
Results were less favourable in a 10-week trial with 45 high-producing Holstein cows. Increasing middlings from 2.2 to 10.9% of diet DM, together with whole cottonseed replacing maize grain and soybean meal, reduced dietary starch from 27 to about 22% DM. Milk yield tended to decrease, milk protein content and yield declined, and feed conversion was poorer, despite greater DM intake relative to body weight in cows receiving the reduced-starch diet without amylase. These responses concern the combined ingredient substitution rather than an isolated effect of middlings (Ferraretto et al., 2011).
Middlings can also replace some forage. In a five-cow crossover experiment, diets containing 15% middlings DM and 38–39% maize silage were compared with a control containing 50% maize silage. Intake and fat-corrected milk production were higher on average with middlings, but ruminal pH tended to be lower. Calcium chloride added to the middlings diets lowered milk fat percentage, while sodium bicarbonate did not improve milk fat percentage, showing that the mineral formulation also affected the response (Wagner et al., 1993).
In a trial using 13 cows, a diet containing 17% middlings DM was compared with diets supplying additional fibre from alfalfa silage or ground maize cobs and with a low-fibre control. Intake and milk yield did not differ. Middlings increased milk fat percentage above the low-fibre control, but rumination was shorter than with additional alfalfa. Judged by the milk-fat response per unit of neutral detergent fibre, middlings fibre was approximately half as effective as alfalfa fibre (Depies et al., 1995).
Protein supplementation was examined in two trials with diets containing approximately 22–25% middlings DM. Cottonseed meal supported milk production similarly to soybean meal; substituting meat and bone meal produced variable responses in milk yield, with no improvement in energy-corrected milk. These historical comparisons illustrate the importance of the complete protein supplement, but did not test the effect of changing middlings inclusion itself (Bernard, 1997).
In a 10-week trial with 192 lactating cows, a ration containing 3.49% middlings DM, soybean meal and urea supported 43.6 kg/day of energy-corrected milk, similar to a ration containing rumen-protected soybean meal (43.7 kg/day). A third ration containing a fermentation by-product supported higher intake and milk production (45.3 kg/day). Because the protein supplements differed in several ingredients, this comparison demonstrates the use of middlings in a productive balanced ration rather than its individual effect on milk yield (Fessenden et al., 2020).
Beef cattle
Middlings provide both energy and protein for beef cattle, but their rapid fermentation and high phosphorus-to-calcium ratio require attention when formulating the ration (Parish et al., 2021). Replacing cereal grain with middlings does not necessarily increase ruminal pH (ZoBell et al., 2003).
In two 84-day growing trials, diets containing about 35.5% middlings DM replaced barley- or maize-based concentrates in maize silage and alfalfa-hay rations without significant changes in daily gain, intake or feed efficiency. In a subsequent 107-day trial with 24 finishing steers, diets containing 35% or 50% middlings DM maintained performance and carcass characteristics. However, in a companion digestion experiment, ruminal pH was lower with the 50% middlings diet than with the corn diet (5.55 versus 5.81), despite similar DM and acid detergent fibre digestibility (ZoBell et al., 2003).
For cattle consuming low-quality forage, the response to supplementation depends on the balance between fermentable carbohydrate and protein. In experiments with 28 yearling heifers and 60 winter-grazing beef cows, middlings supplied 1.7 kg DM/day as an intermediate-carbohydrate supplement, compared with soybean hulls plus soybean meal or barley plus soybean meal. Supplementation improved forage intake and digestion in the heifer experiment, but cow responses varied between years and increasing supplemental carbohydrate could depress forage utilisation. The benefits therefore depended on the basal forage and supplement balance (Bowman et al., 2004).
A more recent study evaluated middlings incorporated into wet maize distillers grains with solubles. In two short crossover experiments, each with four cattle, the blended product replaced unblended distillers grains at 40% of growing-diet DM or 30% of finishing-diet DM. Most measures of intake and digestibility were unchanged; the finishing diet containing the blend produced a higher ruminal pH and a small increase in DM digestibility. These percentages describe the whole blend, not middlings alone, and the study did not measure growth performance (Duncan et al., 2024).
Sheep
Durum-wheat middlings have successfully replaced substantial amounts of conventional concentrate ingredients in balanced pelleted diets for lactating ewes and fattening lambs. Their use at high inclusion rates is supported by specific feeding trials, rather than by a broadly established maximum allowance (Tufarelli et al., 2011a; Tufarelli et al., 2011b).
Forty lactating ewes received pelleted total mixed rations over 18 weeks, including two weeks of adaptation. A ration containing 50% middlings DM replaced a control containing 25.5% maize, with other ingredients adjusted to balance the diets. Milk yield, protein, lactose and clotting properties were maintained, while milk fat percentage and yield increased. A companion experiment with four adult rams found greater fibre digestibility but similar DM, organic matter and protein digestibility (Tufarelli et al., 2011a).
In a 50-day trial with 40 male Comisana lambs initially weighing about 13 kg, a pelleted ration reported to contain 60% middlings DM was compared with a control containing 40% maize. The diets were formulated to provide the same energy and protein concentrations. Daily gain increased from 174 to 199 g and feed conversion improved from 4.29 to 3.74 kg DM/kg gain. Cold carcass weight also increased, while most other carcass traits were unchanged. The middlings came from durum wheat of the Appulo cultivar (Tufarelli et al., 2011b).
Goats
Middlings are a useful energy and protein supplement for forage-fed goats, but their high phosphorus and low calcium contents limit unrestricted use and require mineral balancing (Gurung, 2013).
In a trial with 24 crossbred wether goats, initially weighing 27.4 kg, middlings, soybean hulls or maize gluten feed were supplied at 1% of body weight daily on an as-fed basis alongside freely available orchardgrass hay for 72 days. The control received hay supplemented with soybean meal, and the diets were adjusted to a calcium-to-phosphorus ratio of 1.5:1. Middlings maintained intake, daily gain and nutrient digestibility, while carcass weight was greater than in the control (15.6 versus 14.5 kg). Ruminal pH was lower with middlings (6.23 versus 6.52), but remained above 6 (Moore et al., 2002).
