In China, straw and natural forage are the primary sources of roughage for cattle. However, these feedstuffs often lack sufficient nutritional value to support high milk production in dairy cows, necessitating supplementation. When managed properly, the intake of dry matter and overall feed can be increased. One key metric used to evaluate this is the substitution rate, which measures how much forage or straw is replaced by supplemental feed.
The amount of grass consumed by ruminants while grazing plays a crucial role in their performance. Although pasture has relatively high nutritional value, high-producing cows still require additional nutrients. Supplementary feeding aims to meet these nutritional gaps—especially energy—thereby improving diet digestibility, milk yield, and overall feed intake. In contrast, grazing cows typically consume less than those fed in confinement. Several methods exist to estimate grazing feed intake, including esophageal collection, forage weight difference before and after grazing, canvas bag tests, live weight changes, and direct observation of eating behavior such as daily licking time, eating rate per unit time, and average bite size.
One widely used formula to estimate dry matter intake (IDM/d) for grazing dairy cattle is:
**IDM/d = 0.13FCM + 0.0053W + 0.96G**
(Cox et al., 1956)
Where:
- IDM/d = Daily dry matter intake (kg)
- FCM = 4% fat-corrected milk yield (kg/day)
- W = Body weight (kg)
- G = Daily weight gain (kg)
Another model proposed by Bines et al. (1977) is:
**IDM/d = 0.16M + 0.0113W + 2.45G + 4.25**
Where M = Daily milk yield (kg)
A third equation from NEAL et al. (1984):
**IDM/d = 0.20M + 0.22W**
And a more complex one from Card and Holmes (1986):
**IDM/d = 3.47G + 0.404C + 0.013W - 0.129T + 4.12logT - 0.140M**
Where C = Supplemental feed intake (kg), T = Weeks post-calving
The **substitution rate**, also known as the substitution coefficient, represents the proportion of dry matter intake that is reduced when supplemental feed is introduced. The goal of supplementary feeding is to enhance nutrient availability—such as crude protein, energy, or minerals—in the existing forage or straw. Ideally, the reduction in forage or straw intake should be minimal, indicating a good associative effect between the supplement and the base feed.
When forage is abundant, animals may not reach their full potential intake. Supplementing with energy feeds like grains usually has little impact on forage consumption. For instance, if a cow’s organic matter intake drops from 24 kg to 16 kg per day, the replacement rate decreases from 0.5 to 0.1, showing a significant increase in total feed intake.
Forage supplementation can boost total intake when pastures are plentiful, but the increase is generally smaller than that of the supplemental feed, since the latter reduces forage consumption. If the reduction in forage equals the amount of supplemental feed, the substitution rate is 1, meaning the feed has little impact on production. On the other hand, if the feed does not affect forage intake, the substitution rate is zero, suggesting the supplement plays a major role in enhancing performance.
Energy supplementation can also influence grazing behavior. As energy levels increase, the intake of forage organic matter may decrease from 9.25 kg to 6.42 kg per day. This leads to shorter foraging times, slower eating rates, fewer bites, and less food consumed per bite. Understanding these effects helps optimize feeding strategies and improve both animal health and productivity.
Feed Additives
Feed additives are small amounts of substances added to ordinary feed to improve animal nutrition, enhance physical fitness, and reduce
Feed dosage and effectiveness in disease prevention and control.Feed additives are divided into microbial feed additives and Chinese herbal feed additives.
The use of feed additives is one of the effective means to prevent intestinal diseases and improve the production performance of broilers and laying hens
The feed additive has achieved good application effect in the breeding of piglets, sows and finishing pigs
Feed additives can improve the weight gain rate of meat sheep, beef cattle and other meat ruminants, increase the net meat percentage of the carcass and improve meat quality
The application of feed additives in aquatic products is reflected in the two aspects of food and water purification. Feed additives can improve the microecological balance of aquatic animals, promote growth and development, and play a role in preventing and controlling diseases and improving production performance
We are China Feed Additives supplier and manufacturer,offer low price high quality Amino Acid For Animal Feed,like L-Lysine,L-Leucine,L-Methionine,L-Tryptophan,Taurine,L-Tryptophan,Bacillus Licheniformis,Bacillus subtilis,Bacillus coagulans.
Feed Additives,Feed Nutrition,Amino Acid For Animal Feed,Feed Grade Additive Amino Acid
NANYANG CHENGPENG PHARMACEUTICAL CO.,LTD , https://www.chppharm.com