Reproductive Responses, Metabolic Disorder, Ruminal Fermentation Characteristics, and Milk Production of Postpartum Holstein Cows Fed Steam Flaked of Corn and Barley Grains

INTRODUCTION:

High-producing dairy cows are particularly sensitive to metabolic and reproductive disorders, which are influenced by ruminal microbial activity and the cow’s level of production. In recent years, feed processing has gained growing interest as a nutritional strategy for dairy cattle. Processed grains are fed to improve enzymatic efficiency and microbial access to the endosperm in the rumen and intestine, ultimately enhancing energy supply. Among these methods, steam-flaking—applying heat and steam to grains—is a widely used processing technique. It increases feed nutritional value by physically disrupting the protein matrix and gelatinizing starch, thereby improving grain digestibility in ruminants.

Goals:

Numerous studies have highlighted the importance of using steam-flaked grains on milk production in dairy cows. However, the effects of steam-flaked grains on the reproductive performance of fresh cows have not been thoroughly investigated. Therefore, the objective of this study is to evaluate the effects of feeding steam-flaked corn and barley on rumen fermentation patterns, milk production, and reproductive responses in Holstein dairy cows.

MATERIALS AND METHODS:

In this experiment, 40 fresh cows with an average body weight of 570 kg and a daily milk yield of 30 kg were randomly selected. The cows were divided into four groups (10 cows per treatment) assigned to the following treatments: Ground corn and barley (control), Steam-flaked corn and ground barley (SCMB), Steam-flaked barley and ground corn (SBMC), and Steam-flaked corn and barley (SCB). The basal diet included cottonseed, alfalfa hay, corn silage, soybean meal, canola meal, wheat bran, and supplements, with corn provided either in steam-flaked or ground form at 15 to 17% of the diet dry matter. For the ground grain treatments, the grains were processed using a hammer mill with a 3 mm screen. To prepare the steam-flaked grains, fine particles and seed hulls were first removed using a sieve. Then, the grains were processed in a vertical steam chamber (made of stainless steel) at an inlet temperature of 60°C, an outlet temperature of 212°C, and a pressure of 113.4 bar for 30 minutes. After steaming, the grains were rolled to reach the desired flake density of 360 grams per liter. ​

To assess reproductive performance, the 100-day pregnancy rate, conception rate, days to first service (DFS), and days open (interval from calving to successful conception) were measured. Additionally, the diameter and number of mature follicles were evaluated using ultrasonography. To determine pregnancy status, commercial progesterone test kits were used 21 days after artificial insemination, along with transrectal palpation of pregnancy and ultrasonography on days 35, 60, and 90. ​

Effect of steam-flaked corn and ground barley (SCMB), steam-flaked barley and ground corn (SBMC), and steam-flaked corn and barley (SCB) treatments on DMI, milk yield, and 4% FCM. The reported values for 4% fat-corrected milk (FCM) and milk production are presented across four postpartum intervals: 0–30, 30–60, 60–90, and 90–120 days after calving.

Reduced feed intake during restricted consumption in fresh cows can lead to a negative energy balance, potentially causing health issues and physiological complications. It has also been reported that a severe reduction in body condition score (BCS) can decrease conception rates by up to sevenfold. Logistic regression results showed that feeding steam-flaked grains reduced the incidence of metabolic (e.g., ketosis and acidosis) and reproductive (e.g., pyometra and endometritis) disorders. Specifically, the control group had the highest likelihood of disease occurrence, while the SCB (steam-flaked corn and barley) group had the lowest. Energy status has been shown to influence fertility. Therefore, steam-flaking of grains helps supply adequate energy and protein to fresh cows, supporting resistance against metabolic and reproductive disorders. The reduced likelihood of acidosis was also reflected in ruminal pH levels: the control group had the lowest pH (6.10), while the SCB group had the highest (6.50). Typically, acidosis is defined by a pH below 5.5. It can be inferred that a drop in pH alone is not the sole factor in acidosis; other contributors include rumen overload, reduced blood volume, fluid loss, pregnancy toxemia, loss of salivary bicarbonate, and renal failure (impaired ability to excrete excess hydrogen ions).

The physiological changes that occur during pregnancy significantly affect future milk production, with nutrition during this period playing a key role. The results of this study indicate that feeding steam-flaked corn and barley improved days to first service (DFS), pregnancy rate, and days open. Previous studies have also reported the positive effects of flaked grains in the diets of dairy cows on ovarian function and fertility, which aligns with the findings of this research.

Chart 1. Effect of treatments — steam-flaked corn and ground barley (SCMB), steam-flaked barley with ground corn (SBMC), and steam-flaked corn and barley (SCB) — on the percentage of pregnancy rate within 100 days postpartum, conception rate percentage, days to first service (DFS), and days open.

CONCLUSIONS:

The results of this study showed that feeding steam-flaked corn and barley at 15 to 17% positively affected milk production, milk components, and pregnancy rate.

REFERENCES:

DOI: https://doi.org/۱۰.۵۳۹۸/tasj.۲۰۲۰.۴۳.۳.۲۴۰

Ahmadijoo, N., et al., Reproductive responses, metabolic disorder, ruminal fermentation characteristics, and milk production of postpartum Holstein cows fed steam flaked of corn and barley grains. Tropical Animal Science Journal, ۲۰۲۰. ۴۳(۳): p. ۲۴۰-۲۴۷.