Microbially-Enhanced Soy Protein: An Aquaculture Feedstuff Shows Potential in Dairy Calf Starters

September 7, 2015 05:01 AM
Microbially-Enhanced Soy Protein: An Aquaculture Feedstuff Shows Potential in Dairy Calf Starters

By: Nirosh Senevirathne under the direction and review of Jill Anderson, SDSU Extension

Calf health, performance, and growth rate are critical during pre-weaning and post-weaning. High protein, accelerated growth, milk replacers (MR) have been developed and are used to improve calf performance during the early stages of life. However, one of the main issues of feeding high protein MR, is that they increase feed costs. Another issue is that high quality MR contain proteins such as whey derived from milk sources, which compete with human food markets. Additionally, some research has shown that feeding accelerated MR decreases starter (grain mix or pellets) intake during pre-weaning. Early consumption of high quality starter mixes has been proven to increase rumen development via stimulation of fermentation and papillae development along with potentially improving post-weaning growth performance. With all the controversy related to feeding accelerated growth, high protein MR, research on how to improve quality and the use of calf starter diets has become progressively more important.

With these issues in mind, the Dairy Science Department at SDSU collaborated with Prairie AquaTech (Brookings, SD) to test their newly developed microbially-enhanced soy protein (MESP) as feedstuff for calf starters. This product was originally developed as a protein source for aquaculture feeds in replacement for expensive fishmeal. The MESP is derived from a fungal conversion process starting with soybean meal (SBM). The result is a product with significantly higher protein content, an improved amino acid profile, and significantly higher digestibility in aquaculture trials compared to traditional defatted SBM. Additionally, the process substantially eliminates anti-nutritional compounds inherent to SBM. The microbial component has shown to enhance the long-term innate immune system in fish, similar to yeast or other health supplements. As calves have sensitive, developing digestive systems, it was hypothesized that feeding MESP with its unique combination of beneficial properties could improve utilization of starter and growth performance.

To test this hypothesis, a feeding trial was conducted to evaluate growth performance of calves fed starter pellets with MESP and traditional MR (20% CP, 20% Fat) or accelerated growth, high protein MR (28% CP, 18% Fat) compared to calves fed starter pellets with soybean meal (SBM) and accelerated growth, high protein MR. The study was conducted with 36 Holstein calves in individual hutches at the SDSU Dairy Research and Training Facility.

Treatments were:

  • MSPA = MESP pellets with accelerated growth, high protein MR
  • SBMA = SBM pellets with accelerated growth, high protein MR
  • MSPT = MESP pellets with traditional MR

Both pellets were similar, but had 23% MESP or 23% SBM (dry matter basis) included. Calves were fed 0.75 lb of MR during week one and 1 lb of MR during weeks 2-5 (twice per day), 1 lb of MR once per day during week 6, and weaned at day 42. Pellets and water were available at all times. Intakes and fecal scores (1=firm, 4=liquid) were recorded daily. Frame sizes and body weights were measured 2 consecutive days every 2 weeks approximately 3 hours post feeding. During week 12, fecal grab samples were collected 5 times a day for 3 days and then composited by calf for analysis of total tract nutrient digestibility.


Averages for body weights, average daily gains, intakes, and gain-to-feed are shown in Table 1. Body weights over the 12-week trial are also shown in Figure 1. Final body weights were similar for MSPT and SBMA fed calves, and greater for calves fed MSPA. Because of treatment effects on average daily gain and intakes, gain-to-feed ratios (feed efficiency) were improved in the MSPA and MSPT treatments compared to SBMA. Rates of gain for frame growth measurements (data not shown) were the same across treatments. Calves fed MSPT had higher total tract digestibility of crude protein and acid detergent fiber (ADF) as compared to calves fed SBMA (Table 1). It is quite possible that the differences in digestibility are related to differences in rumen development. Despite high protein intakes, overall incidences of scouring (diarrhea) were low and fecal scores across treatments averaged 1.16, indicating firm consistency. Feed cost estimates for this trial showed an economic advantage of approximately $40 per calf with feeding MSPT compared to SBMA to raise calves to 12 weeks of age. There was some increase in feed cost ($22 per calf) when feeding MSPA compared to SBMA, but this may be offset by increased total body weight gains and improvements in long-term performance.


Results show an additive benefit of feeding calves high protein MR and MESP on weight gain and gain-to-feed ratio over high protein MR and SBM. Calves fed MSPT had comparable growth performance to calves fed SBMA, with an increased gain-to-feed ratio, especially after weaning. A feed cost assessment demonstrates there is potential to feed MESP and decrease overall feed costs while maintaining growth performance. Meanwhile, net usage of SBM per dairy calf is increased because of the conversion rates of SBM to MESP. Therefore, use of the MESP product in dairy calf starter would be beneficial to dairy producers and soybean growers. Further research with different feeding scenarios is needed, but results of this study indicate that microbially-enhanced soy protein (MESP) shows a competitive advantage and excellent potential as an ingredient in dairy calf starter.


This research was funded by the South Dakota Soybean Research and Promotion Council and supported by the South Dakota Agriculture Experiment Station.

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