Precision feeding in beef production – enhancing reproductive success with strategic supplementation

By international ruminant nutrition consultant Dr. Hinner Köster

In the world of beef production, precision feeding is a crucial element that can significantly improve the profitability and efficiency of operations. With feed costs accounting for 50-70% of total input expenses, optimising nutritional strategies is essential for cattle farmers aiming to enhance reproductive rates and overall productivity.
Knowing when to supplement cows and what form of supplement will work in a given time is crucial.

International ruminant nutrition consultant Dr. Hinner Köster presenting at the Zimbabwe Herd Book Beef School

Factors affecting reproductive performance

To develop effective supplementation strategies for breeding animals, it’s vital to consider a wide range of interactive factors, including:

• Feed Intake
• Physiology
• Environment
• Management
• Production
• Reproduction
• Genetics
• Animal Condition
• Profits

Understanding the total picture allows farmers to implement strategic nutritional interventions that can create a snowball effect; improving reproduction rates and contributing to greater profitability.

Profitability of the cow/calving operation is influenced by the percentage of cows calving every 12 months and a primary reason for low reproduction rates is limitation of the right nutrition, leading to poor body condition scores (BCS).

Body Condition Score (BCS) as a management tool

BCS is an essential management tool for cattle operations. It is a simple procedure that, if used correctly, can ensure the management of a successful beef cow-calf operation. Here's a breakdown of BCS on a 1-9 scale and what it indicates about an animal's health:

1. Emaciated. Shoulder, ribs and back are visible.
2. Very thin. Some muscle, no fat deposits.
3. Thin. Some fat deposits, ribs visible.
4. Borderline. Fore ribs not noticeable.
5. Moderate. 12th and 13th ribs not visible
6. Good. Ribs covered, sponginess to tailhead.
7. Very good. Abundant fat on tailhead.
8. Fat. Fat cover thick and spongy.
9. Obese. Extremely fat throughout.

Research has shown a direct correlation between body condition during the breeding season and conception rates, further emphasising the importance of maintaining appropriate BCS levels. There is also a direct link on effect of BCS at calving and subsequent pregnancy rates, particularly in first calf heifers.

Economic feeding strategies for breeding cows

Regardless of the scoring system or monitoring system, understanding the nutritional needs and timing of supplementation is paramount. This involves knowing:

• When cows can be maintained on a decreasing plane of nutrition
• When they should be maintained on an increasing plane of nutrition
• When cows may be kept on a maintenance diet

Nutritional phases of a beef cow production cycle

Period 1: Shortly after weaning to mid-gestation

A time of lowest requirements. This is an optimal time to adjust a cow’s diet and either decrease or increase her condition. Cows require very little in terms of nutrients to maintain their metabolism. If a cow is in poor condition, there is no better stage to adjust her feed regimen to increase her condition. Supplementation before calving can significantly impact pregnancy rates. Get the cow’s body condition back to optimum to get her reproduction back on track.

Period 2: 60 to 90 days pre-calving

Rapid foetal growth (of up to 0.5kg of gain a day shortly before parturition) demands increased nutrition. Cows also require several other physiological mechanisms to occur to prepare her for lactation. This means adjusting a cow’s condition needs more feed. Adjustments during this phase require careful planning, especially in winter when feed quality can decline and supplementation becomes expensive.

Period 3: Calving to rebreeding

Nutritional needs peak, as cows must support milk production while regaining any weight loss shortly before and after parturition as well as to repair her reproductive tract to become pregnant within three months after birth.

This stage often sees cows consuming as much feed as she can to support herself. Adjusting body condition at this stage often is futile. Cows are usually grazing and tend to consume their full protein, vitamin and mineral requirements. However, the grass is often lush with a high percentage of moisture (usually with the first rains); occasionally this can cause a deficiency in energy.

Period 4: Lactation

The highest nutrient demand occurs here. Innovative feeding practices are essential to manipulate condition effectively.

Impact of nutrients on reproductive performance

Insufficient intake of energy, protein, vitamins, and macro and micro minerals can lead to suboptimal reproductive performance.

Economic feeding strategy of the breeding cow

Make maximum use of nutrients in natural and established pastures, stover, hay or silage. Supplementation must complement the roughage source. It is critical to understand the effect of supplemental nutrients on the intake and digestion of the roughage source.

With low-quality roughage, your goal is to increase your cow’s intake and digestion.

Supplemental nutrition on dry pastures

This usually coincides with periods 1, 2 and part of period 3 and incorporates lower-quality roughage sources such as dry pastures, standing hay, stubble and stover. The limiting factor in this instance is insufficient protein for the rumen microbes, especially when no green material is present. Lower digestibility means low intake and low animal production levels.

Supplemental nutrition on green pastures

This usually coincides with periods 3 and 4. With green pastures there are sufficient protein levels for rumen microbes and often to maintain a certain level of animal production.

Supplementing low-degradable protein to maintain higher production (lactating cows, pregnant heifers, growing calves) in this instance usually results in a positive response.

Here, the problem can be often there is too much protein (especially degradable) that is used inefficiently; there is not enough readily available energy to use a large amount of soluble protein and insufficient minerals.

Protein supplementation strategies

Protein is the “first” limiting nutrient on low-quality pastures: the protein used by the rumen microbes rather is the first limiting nutrient within winter maintenance supplements. Rumen degradable protein (RDP) is not total protein.

Manure can be used as a visual tool to ascertain if digestion is taking place (too firm a pat indicates there is not enough protein in the feed).

The overfeeding of RDP either as protein or urea/ammonia is associated with decreased pregnancy rates in female dairy and beef cattle. Exposure to high levels of ammonia or urea may impair the maturation of oocytes; subsequent fertilisation or maturation of developing embryos.

Supplying adequate energy for excretion of excess ammonia or urea may prevent decreases in fertility in dry cows or heifers.

When it comes to energy supplementation in natural grazing, no grain supplementation is needed if the goal is only to achieve better utilisation of lower-quality pastures. Pastures must have sufficient energy, though, for maintenance of condition. Feed your cows grain and other energy sources if the goal of your supplementation is to achieve additional production above maintenance on pastures. This covers using licks and limited concentrates.

For energy supplementation on natural grazing, the correct energy levels and types with protein in supplements on pastures efficiently improves growth, feed conversion and milk production. The intake and composition depend on the required/targeted production level and with breeding animals, it needs to be managed.

For energy supplementation on natural grazing, production licks (not maintenance licks) and limited concentrates need to be given to cows with calves, at least until rebreeding. They also need to be given to dry pregnant cows at any stage not in optimal body condition, at least 60-90 days before calving. Also needed for first-calf heifers and growing animals. For growing animals, manage their intakes to achieve average daily gain targets.

Mineral and vitamin supplementation

Minerals are divided into two groups - macro and micro (or trace).

Macro minerals are essential for all physiological systems, especially phosphorus.

Larger amounts are required especially for growth (bones, teeth), immunity, enzyme functions, nerve transmissions, water balance in the cells.

Macro minerals are calcium, phosphorus, magnesium, potassium, sodium, choline and sulphur.

Subclinical shortages are the biggest problem as you do not see any symptoms.

Phosphorus is the most common mineral shortage and a shortage leads to non-visible production losses, decreased reproduction, milk production and decreased growth.

Micro or trace minerals are important in animal health and production. Much smaller quantities are needed and they are used all over the body. Problems with trace minerals occur due to mineral interactions in the rumen therefore ratios are critical. Essential trace minerals include copper (Cu), manganese (Mn), zinc (Zn), selenium (Se), iodine (I), cobalt (Co), iron (Fe), chromium (Cr), molybdenum (Mo), fluorine (F), silicone (Si), vanadium (V), nickel (Ni), tin (Sn) and arsenic (As).

Cows need these, especially four weeks before calving and breeding.

Vitamins

Supplementation before and after calving can increase conception rates. Winter hay-based diets or low-quality grazing can become deficient in vitamin A.

Vitamin A deficiency does occur naturally in cattle grazing dry winter grazing or consuming low quality crop residues and forages. Most of the vitamins (C, D, E and B Complex) are either synthesised by rumen microorganisms, the body (vitamin C), are available in common foods and are not of concern under normal conditions.

Management strategies for optimising reproduction

Ensure sufficient energy is available to support reproduction.

1. Ensure cows achieve a BCS of 5 and heifers a BCS of 6 by calving, ideally 60 days beforehand.
   Maintain cow body condition from calving through breeding for cows in proper body condition, and increase body condition in cows that are below optimal BCS at calving. Feed thin cows and first-calf heifers in a separate group(s) from the main herd. Provide energy supplementation from the most economical local source.
2. Provide optimum level of dietary protein. Provides sufficient protein to the rumen bacteria for adequate function. Avoid over-supplementation of protein.
3. Base mineral supplementation on forage mineral content and local deficiencies. Supplement phosphorus when needed. Pay attention to trace mineral levels especially copper, selenium, magnesium and zinc.

Achieving success in beef production requires careful daily attention to nutritional details and precision feeding. Implementing strategic supplementation can enhance reproductive performance will ultimately lead to a more profitable and sustainable beef cattle operation.

This article is fourth in a series that shares highlights from this year’s Zimbabwe Herd Book’s annual Beef School, held in September. Spread over three days, the Beef School is an annual event held in Bulawayo, which allows attendees to network with fellow beef producers and sector stakeholders. It covers a multitude of subjects, with each session designed to provide actionable advice and insights that can be directly applied to participants’ operations.