Invasive crayfish useful for feeding chickens
The Procambarus clarkii crayfish, one of 300 invasive species recorded in Colombia is currently abundant in several municipalities of the Province of Valle del Cauca.Bogotá D. C., 18 de septiembre de 2015 — Agencia de Noticias UN-
This species of crayfish was introduced into Colombia from United States in 1985. Photo: Personal file
A doctorate degree research project performed at UNal-Palmira identified the protein level of this crustacean for the benefit of animal nutrition and determined they would transform this crayfish into a nutritional meal feed for growing and finishing chicken rations.
In United States, its place of origin it is well appreciated for human consumption and can reach up to 20 cms (7.8 in.) thanks to diverse environmental and seasonal conditions. In Colombia, although the tropical conditions help its reproduction they do not reach the size and weight required for international marketing.
As claimed by Researcher and UNal-Palmira Agrarian Science PhD Elba Fiorella Gómez Cestagalli whom is devoted to studying this species and assessing the exploitation alternatives as a way to control its uncontrolled spread across the region.
This is how she reached to a crayfish meal solution. She visited many different water sources to determine where the species was present and later chose eight locations to capture the animals with catangas (baskets) near Palmira.
Afterwards she morphologically characterized the species and described its population density. They also carried out a survey with 38 people of the region to assess how much the species was acknowledged.
Although there is still no official count, they obtained 321,637 specimens in 27 weeks. They were then transformed into crayfish meal and several variables were tested including acceptance by hens and chickens, as well as its digestibility.
To transform the crayfish into meal they carried out a steam precooking procedure at 120° C (248º F) for three minutes, later it was air dried with moisture free air at 40° C (104º F) for 72 hours, then it was ground and vacuum packed.
To assess the new food they determined two supply models: The first consisted of providing 70g of crayfish meal in a container and the normal amount of regular dry food in another container for a total of 120g per chicken per day; the second method was to blend the meal with traditional dry food at the same concentration.
Additionally they gathered and counted chicken eggs for seven straight days two times a day (morning and afternoon) and weighed and classified them individually.
The meal proved to be beneficial because it influences the color of the yolk. The eggs obtained were labeled as functional food as it helps improve body functions due to its high astaxanthin (antioxidant keto-carotenoid) and omega 3 and 6 content.
During week 62 of production, chickens preserved their development level above 85%, when it is considered that at this age they begin to decrease yield. Under these conditions they did not fatten and maintained their ideal weight.
Furthermore calcium content in the meal avoids providing additional calcium to their diet. Chickens achieved greater weight, although due to the astaxanthin their skin turned to a salmon pick color; this according to the researcher could have a negative impact on the market as consumers are accustomed to the traditional yellow color.
The journey of a raider
In 1985, the crayfish was brought to Colombia by the firm Agropecuaria Heliodoro Villegas Sucesores S.A., as an experimental species for human consumption. However in 1988, after some controlled experiments there was an accidental escape which initially only reached Palmira but then it spread through the Cauca River to other municipalities such as Santiago de Cali, Jamundí, Yotoco, San Juan Bautista de Guacarí and Guadalajara de Buga.
These crayfish build their very long galleries in form of a U in the walls of irrigation ditches, ravines, water reservoirs, fishing lakes, lagoons and marshes, impacting their structure and altering established ecosystems.
This crayfish is an omnivore and scavenger, in its voracious appetite it feeds on worms, fish eggs, frogs, salamanders, and small animals as well as zooplankton and phytoplankton. Besides displacing other species from its habitat, it is also bearer of the Aphanomyces astaci water mold producing aphanomycosis or crayfish pest, a disease that impacts endemic species.
Read the article in its entirety in Spanish at UN Periódico:(Por: Fin/HA/DMH/CA