Poultry litter is a mixture of bedding materials and enteric bacteria excreted by chickens, and it is typically reused for multiple growth cycles in commercial broiler production. Thus, bacteria can be transmitted from one growth cycle to the next via litter. However, it remains poorly understood how litter reuse affects development and composition of chicken gut microbiota. In this study, the effect of litter reuse on the microbiota in litter and in chicken gut was investigated using 2 litter management regimens: fresh vs. reused litter. Samples of ileal mucosa and cecal digesta were collected from young chicks (10 days of age) and mature birds (35 days of age). Based on analysis using DGGE and pyrosequencing of bacterial 16S rRNA gene amplicons, the microbiota of both the ileal mucosa and the cecal contents was affected by both litter management regimen and age of birds. Faecalibacterium, Oscillospira, Butyricicoccus, and one unclassified candidate genus closely related to Ruminococcus were most predominant in the cecal samples, while Lactobacillus was predominant in the ileal samples at both ages and in the cecal samples collected at day 10. At days 10 and 35, 8 and 3 genera, respectively, in the cecal luminal microbiota differed significantly in relative abundance between the 2 litter management regimens. Compared to the fresh litter, reused litter increased predominance of halotolerant/alkaliphilic bacteria and Faecalibacterium prausnitzii, a butyrate-producing gut bacterium. This study suggests that litter management regimens affect the chicken GI microbiota, which may impact the host nutritional status and intestinal health.

The intestinal microbiota of broiler chickens and the microbiota in the litter have been well studied, but the interactions between these two microbiotas remain to be determined. Therefore, we examined their reciprocal effects by analyzing the intestinal microbiotas of broilers reared on fresh pine shavings versus reused litter, as well as the litter microbiota over a 6-week cycle. Composite ileal mucosal and cecal luminal samples from birds (n ‫؍‬ 10) reared with both litter conditions (fresh versus reused) were collected at 7, 14, 21, and 42 days of age. Litter samples were also collected at days 7, 14, 21, and 42. The microbiotas were profiled and compared within sample types based on litter condition using PCR and denaturing gradient gel electrophoresis (PCR-DGGE). The microbiotas were further analyzed using 16S rRNA gene clone libraries constructed from microbiota DNA extracted from both chick intestinal and litter samples collected at day 7. Results showed significant reciprocal effects between the microbiotas present in the litter and those in the intestines of broilers. Fresh litter had more environmental bacteria, while reused litter contained more bacteria of intestinal origin. Lactobacillus spp. dominated the ileal mucosal microbiota of fresh-litter chicks, while a group of bacteria yet to be classified within Clostridiales dominated in the ileal mucosal microbiota in the reused-litter chicks. The Litter condition (fresh versus reused) seemed to have a more profound impact on the ileal microbiota than on the cecal microbiota. The data suggest that the influence of fresh litter on ileal microbiota decreased as broilers grew, compared with temporal changes observed under reused-litter rearing conditions.

The standardized ileal amino acid digestibility (SIAAD) of 5 plant-based ingredients was determined in 5- and 21-d-old broiler chicks and turkey poults. Two diets (N-free diet, NFD, and a highly digestible protein diet 10% casein, HDP) were fed to determine ileal endogenous amino acid flow, and each was used for endogenous amino acid correction for the plant-based ingredients. The plant-based ingredients evaluated were 2 samples of corn distillers dried grains with solubles (light and dark DDGS), canola meal, corn, and soybean meal. Each diet was fed for 5 d to 6 replicate cages containing 30 or 8 birds, which were sampled on d 5 or 21, respectively. For chicks, apparent ileal amino acid digestibility increased with age for all the feed ingredients. After standardization, SIAAD increased with age when chicks were fed DDGS and corn, but not soybean meal or canola meal. For all the feed ingredients evaluated, SIAAD values for both methods of standardization were not different at d 5. However, the HDP method resulted in greater SIAAD values for most of the amino acids in light DDGS, canola meal, and corn (d 21). In poults, the apparent ileal amino acid digestibility values increased with age for all the feed ingredients except the dark DDGS and canola meal. After standardization, there was no effect of age on amino acid digestibility in all the feed ingredients evaluated, with the exception of corn. Within a particular age (d 5 or 21), both methods of standardization resulted in similar amino acid digestibility values except for corn, for which the SIAAD values were greater (NFD method) in 11 amino acids. Results from this study showed that age-appropriate endogenous amino acid standardization is necessary and, in some cases, results in no age-associated differences in amino acid digestibility. With the exception of corn, standardization of amino acid digestibility with ileal endogenous amino acid flow from birds fed an NFD or HDP did not differ for most plant feedstuffs.

The objective of this experiment was to characterize the relationship between growth and skeletal development in commercial broilers as a function of both age and BW. From hatch through 43 d, birds were randomly selected weekly from the same commercial flock for measuring BW, tibia, and femur characteristics. Final BW was 1.8 kg for females and 2.1 kg for males. The fat-extracted weight of the tibia and femur increased proportionately with BW through 43 d of age. Length and width measures as a proportion of their final values at 43 d increased more rapidly than relative changes in BW. The length of the femur as a function of BW reached a plateau at 1.5 kg (35 d of age), whereas the length of the tibia did not plateau through 43 d of age. Differences in width measures between the two long bones were not apparent as BW increased through 43 d of age. The ash percentage of the diaphyseal region (mid-10% of bone) was consistently greater in the tibia than the femur from 15 to 43 d (P < or = 0.05). Differences in mineralization rates and growth characteristics suggest that the functionality and integrity of the femur should not be assumed solely from tibia measurements.

Accurate estimation of ileal endogenous amino acid (EAA) losses is important when formulating diets on a standardized ileal digestible amino acid basis. In addition to the undigested and unabsorbed amino acids of dietary origin, amino acids of endogenous origin, which can be basal or diet specific, are found in digesta. The improvement in the techniques used in amino acid analysis as well as a shift from sampling excreta to ileal digesta has resulted in more accurate amino acid digestibility coefficients. Despite this, however, it is important to determine the amino acids in the digesta that are of endogenous origin. Although the need for standardization and its associated advantages is still subject to debate, it is important to evaluate how values from various methodologies compare. Several methods have been used to estimate ileal EAA flow. The classical methods, including the regression method, the use of nitrogen-free diet (NFD), and the fasted cecectomized rooster method, are the most widely used. The criticisms with the last 2 methods are that birds are not in a normal physiological state and the ileal EAA flow is, therefore, underestimated. Different methods have resulted in different endogenous flow estimates, with the NFD method having the lowest values when compared with flows from the regression and highly digestible protein methods. In addition to the influence of methods on ileal EAA flows, the influence of the age of the birds on flow is important. Data on EAA losses are copious in the literature; however, variation in data across and within laboratories calls for investigation of factors contributing to the variation. This review compares results from different methods and examines the issue of repeatability and consistency of EAA losses data from different laboratories. Finally, composition of an NFD for estimating EAA losses is proposed.