Reducing FCR in broilers requires timing of immunity

//27 Apr 2011
Enabling broilers to operate at maximum metabolic efficiency is a realistic goal that will be affected in part by vaccine choices, according to a leading poultry nutritionist.
Dr. Robert Teeter, of Oklahoma State University, has extensively studied energy utilization in broilers with the aid of sophisticated metabolic chambers. At a recent respiratory health conference, he pointed out what broiler producers know well: that the lion’s share of total production costs - from 60% to 75% - go to feed. In fact, one point of FCR is valued at over $54 million annually for the broiler industry.

Considering the rising cost of feed and the fact that further gains in feed formulations are becoming increasingly difficult, producers need to find non-nutritive factors that can be manipulated to improve energy utilization. In short, they need management strategies that minimize calories used and the energy lost by broilers, he said.

Experiments by Teeter and colleagues have already demonstrated that the FCR for birds raised on the same ration to the same weights can vary from 1.63 to 2.11, depending on differences in bird behavior that are affected by management. They have also identified management practices that affect bird activity and result in energy loss or retention. Feeding pellets instead of mash, for instance, reduces bird activity and is especially beneficial later in the production cycle, when birds eat the most. Birds raised with 12 hours versus only 1 hour of dark need less feed to reach market weight, the investigators have found.

Impact on developing immunity
Additional improvements in caloric savings can be achieved with management strategies aimed at manipulating the development of immunity, Teeter said at the conference, held in Ocean City, Maryland, and sponsored by Intervet/Schering-Plough Animal Health. He and colleagues have discovered that a coccidial challenge late in the broiler’s life that results in even minor coccidial lesions has a significant, negative impact on performance values such as live weight, average daily gain and FCR. In contrast, when birds are vaccinated at 1 day of age with the live coccidiosis vaccine Coccivac-B, they develop immunity against coccidiosis early and the impact on performance is minimal.

Similar manipulations in the timing of immunity against respiratory diseases, coupled with other management changes designed to conserve energy, can lead to further gains in performance, enabling birds to attain their genetic potential, said Teeter, who is embarking on studies to discover which vaccines are “kinder and gentler to the bird” and induce immunity for the least calorific cost. “Today’s bird is operating at about 51% efficiency; 66% metabolic efficiency is possible, which means that an FCR of about 1 is also possible,” he said.

Field evidence
Field evidence that the vaccine chosen can affect performance came from Dr. Jeff Courtney, of Pilgrim’s Pride. During a panel discussion at the conference, Courtney reported that the use of the recombinant vaccine Innovax-ND-SB, which his company administers in ovo during winter months to help prevent Newcastle and Marek’s diseases, resulted in a “measurable decrease” in feed conversion and condemnations at one of the company’s complexes; the incidence of femoral head necrosis also decreased.

There is “no doubt” that use of Innovax-ND-SB was associated with improved performance, which he attributes to less stress. Eliminating the use of a live ND vaccine, which can result in side effects, and using the recombinant vaccine instead, which causes no side effects, put less stress on broilers, he said. “I’m a proponent of the recombinant vaccines. Anything we can do to decrease stress is to the benefit of the bird. Decreased reactions mean decreased stress,” said Courtney.

[Source: Newsletter Intestinal Health Centre for Poultry issue #5 – Intervet Schering- Plough Animal Health]