Manitoba Agriculture, Food and Rural Initiatives

Grass  Fed  Beef – An Argentinean Experience

Source: Juanita Kopp, Farm Production Extention Specialist – Beef,  MAFRIJuanita was one of eight delegates of the ‘Argentina Grass-Fed Beef Technology Transfer Mission’ (March 1 – 11, 2008). The project was initiated by the Manitoba Grass Fed Beef Association, funded by the Manitoba Functional Food Opportunities Program and supported by Manitoba Agriculture, Food and Rural Initiatives.

Grass Fed Beef –An Argentinean Experience

Argentina is synonymous with grass fed beef; they would rarely use grain to finish their cattle. But times are changing, due to high grain prices most of the ranches we visited were going to rip up pastures and plant soybeans, followed by sunflowers or corn. But the Argentinean culture is dependant on beef. About 3.1 million tons of beef is produced per year (6 billion pounds) and most of it is consumed in the domestic market.

Pasture Management

The campo managers or owners send the cow herds south or west to the poorer lands, where native ranges are prevalent. After the calves are weaned they send them back to the more fertile lands of the Pampas, there they will be backgrounded and later finished.  Stocking densities were quoted as kg per ha and the average weight of stocker cattle is 300 kg and the stocking density is 1100 kg/ha or about 3.5 head/ha. To increase their stocking rates in the Pampa region, and to free up more land for annual crops, they supplement the cattle with cracked corn, sunflower pellets, hay and or silage at a rate of   0.5 to 1% of body weight. 

 Gains on Pasture

Attentive graziers monitor their cattle gains throughout the summer to see when the cattle gains are lower and subsequently find ways to manage the late summer slump and fall pasture quality decline. Most of the pastures we toured were alfalfa-grass pastures, but the cattle also grazed corn, sorghum and annual crops.   The farm managers targeted average day gains of 600 to 800 g/hd/day or more. Dry matter intake on lush alfalfa-grass pastures can be a problem, to offset this they fed good quality hay to increase the DMI of the cattle with in turn increases their ADG.

 To optimize animal gains, the amount of soluble carbohydrates (SCH) and crude protein (CP) need to be balanced. Dr. Anibal Pordomingo, a beef researcher with INTA (National Institute of Agricultural Technology, Anguil, Argentina), stated that the SCH content of forages is very important for animal gain. Evaluating forages only by measuring the % ADF and % TDN is not the most accurate way of predicting animal performance.

 Protein is required by the rumen microbes to grow; the microbial protein that is produced in the rumen later provides protein to the animal.  Nitrogen is quickly released in the rumen after it is consumed; therefore the presence of an easily digested carbohydrate (SCH) is needed by the microbes to capture the nitrogen. The greater the SCH content the better the match with protein supply and the greater the chances of capturing the nitrogen for microbial growth. The closer the protein to SCH ratio is to 1:1 the better the potential gains.

 In a presentation that Dr. Pordomingo gave at the 2006 Manitoba Grazing School, the following table describes the idea forage chemical composition needed to achieve high individual animal gains

 Desired composition of green forages for high individual cattle gains

Nutritional Components	Values	Nutritional Components	Values
Dry Matter, %	Above 20	ADF, %	Below 25
Crude Protein, %	Range from 14 to 18	In vitro Digestibility, %	Above 65
Soluble Carbohydrates, %	Above 18	Dry Matter Intake, % live weight	Above 2.5
CP:SCH	Similar or below 1	Metabolizable Energy Concentration, MCal/kg DM	Above 2.4
NDF, %	Below 40

Adapted from the Proceedings from the Manitoba Grazing School 2006, Nov. 29 & 30, 2006, Keystone Centre, Brandon, Manitoba.