Brazil: Study shows probiotics boost broiler growth, bird well-being

A team of researchers in Brazil explored the use of probiotics to improve broiler chicken production and wellbeing without feeding antibiotics. The study was published in the Journal of Applied Poultry Research​​​.

“The present research assessed the effect of supplementation with different doses of probiotic on the performance, yield of the carcass and its parts, myopathies, intestinal quality, and well-being of broiler chickens."​

The researchers found that birds on a diet with the recommended dose of a probiotic, rather than half or a double dose, had better performance, carcass yield, behavior and well being than birds on other feeds.

Birds receiving the probiotic had improved feed conversion and production efficiency compared to those receiving a traditional growth prompter, they said. Birds on the probiotic-supplemented diets had reduced incidences of myopathies including “spaghetti breast” ​and were found to be calmer during wellbeing trials.

“Under the conditions in which this experiment was conducted, the probiotic replaces the growth-promoting antibiotic, since it promoted equal or better results than the antibiotic,”​ the authors added.

Focusing on antibiotic reduction​

Intestinal health in chickens has to be addressed to allow maximum nutrient absorption and proper animal development, they stressed.

When there is an intestinal imbalance, including enteritis or dysbacteriosis, birds can display reduced weight gain and feed efficiency, they said. “With such imbalances, intestinal mucosa thickness and crypt depth increase, villi decrease, and rapid passage of digesta occur, which impairs the proper absorption of nutrients.”​

Myopathies also present a problem for producers, but the easiest way to prevent their development is to have a low-stress environment for birds, they said.

These challenges have increased the search for feed products that help modulate birds’ intestinal microbiota, a hunt accelerated by increasing regulatory pressure on the use of performance-enhancing antimicrobials in livestock production.

Probiotic story ​

Products such as enzymes, prebiotics, probiotics, organic acids and symbiotics have all come under the spotlight in the search for alternative feed additives that can support poultry gut health.

“In bird farming, Lactobacillus, Bacillus, Bifidobacterium, Pediococcus, Streptococcus, and Enterococcus bacteria and yeasts such as Saccharomyces cerevisiae are used as probiotics,”​ they said.

Newly hatched birds receiving feed additives have shown improved resistance to the colonization of pathogens, improved local immune response in the intestine, reduced pathogen load, better sanitary status and limited risk of transmitting pathogens, they said.

“Probiotics can be characterized as living microorganisms that provide benefits to health; hence, they contribute to animal well-being, as long as they are administered [at the correct dosage level],”​ the researchers said. “Such additives modulate the microbiota through competitive exclusion by adhering to action sites in the intestine and by producing substances with antibacterial action.”​

Feeding trial highlights​

During the 42-day feeding trial, 2,000 birds received one of four diets, the researchers said.

The diets included a negative control (NC) where the corn and soybean meal-based diet included the growth promoter chlorohydroxyquinolines, a diet with a half dose of the probiotic (HD) and chicks were inoculated at the hatchery against Marek disease, a positive control (PC) where birds were inoculated and receive the full dose of probiotic and a diet with double the dose of probiotic (DD) and inoculation, they said.

“The probiotic used is a commercial product in powdered form containing a mixture product composed of 3 × 109 colony forming units (cfu)/g Pediococcus acidilactici and 2 × 109 cfu/g Lactobacillus plantarum,” ​they added.

Birds were weighed on days 21, 35 and 42 to establish body weight gain (BW), feed intake (FI) and feed conversion ratio (FRC) and mortality was noted daily, they said. On day 36, a selection of birds was harvested to check intestinal characteristics including gizzards erosion, coccidiosis, intestinal wall hyperemia, intestinal tonus, mucus, intestinal consistency, color and the presence of gas.

On day 35, three well-being tests were conducted including latency-to-lie (LTL) a modified touch test and a grab test, the researchers said. “Latency-to-lie is a method employed to assess the time the bird takes to sit when exposed to an uncomfortable situation that is strange to its rearing,”​ they added.

“For the modified touch test, an assessor entered the pen and, after 3 min, extended his or her arms and counted how many animals could be touched,” ​they said. “For the grab test, the animals were taken in groups of 3 to a calm fenced area with 1 m diameter and, after 3 min, the assessor tried to hold the birds, simulating them being grabbed, and rating the response.”​

At the end of the feeding trial a selection of birds on all diets was harvested to assess carcass and part quality, they said. Breasts were also checked water-holding capacity and for frequency of myopathies including wooden breast, deep pectoral myopathy and spaghetti meat.

Results​

Overall, birds on the PC diet had improved FI, BW gain, livability and production efficiency factor (PEF) by day 21 and throughout the entire feeding trial they had better FI, FCR and PEF, the researchers said. “Regression evaluations demonstrate that PC—diet with probiotic (dose recommended by the manufacturer), provided better results of weight gain, FI, feed conversion, and, mainly, PEF and viability."​

Birds receiving the probiotic displayed improved intestinal quality compared to the negative control, they said. Birds on the PC and DD diets had better live weight and DD birds had improved yields for whole breast and breast fillet.

Spaghetti breast was most prevalent in birds on the negative control diet, they said. However, wooden breast was found in birds on the DD diet.

Following a series of welfare tests, birds on the diets with added probiotics were calmer, the researchers said.

“The LTL test showed that those birds were able to stand for longer under stressful conditions (standing in water) compared with those that did not consume the commercial probiotic,” ​they said. “In the modified touch test and grab test, the birds fed diets containing antibiotics had the worst results, which shows they were less calm.”​

Source: Journal of Applied Poultry Research​

Title: Productivity and Well-Being of Broiler Chickens Supplemented with Probiotic​

Authors: I.C.L.A. Paz, I.C.L. Almeida, L.T. La Vega, E.L. Milbradt, M.R. Borges, G.H.C. Chaves, C.C. dos Ouros, M.I.L. da Silva, F.R. Caldara, R.L.A. Filho

DOI: doi.org/10.3382/japr/pfz054​​