Estimation of bone mineral density and breaking strength of laying hens based on scans of computed tomography for body composition analysis.

1. The objective of this study was to evaluate the prediction potential of a computer tomography (CT) data collection protocol for determining total body composition used for analysis of tibiotarsal bone quality features. 2. The CT image acquisition was performed on 54 healthy TETRA SL genotype laying hens at 90 weeks of age as well as in the 69th week of the egg production period in vivo and their tibiotarsal bones, ex vivo. 3. Breaking strengths and ash content of the tibiotarsal bones were estimated based on the calculated mineral density of skeletal and tibiotarsal bones by means of CT with an estimation accuracy R2 0.963 and 0.975, respectively. 4. In conclusion, the current investigation demonstrated that the acquisition protocol of CT for total-body composition analysis has a good potential for measuring the mineral status and breaking strength of the reference bone in laying hen.

Digestibility and metabolism of dietary guanidino acetic acid fed to broilers.

In two feeding experiments the retention of supplemental guanidine acetic acid (GAA) in broilers was investigated. In both experiments, the same three treatments were used; the basal feed was supplemented with 0, 0.6, or 6.0 g GAA per kg of feed. While in a growth study (experiment 1) day-old, male Ross 308 broilers were fed diets for 35 days, these diets were fed for only 8 days to fistulated broilers 34 days of age in a balance study (experiment 2). Feeding 0.6 g/kg GAA did not improve growth performance whereas 6.0 g/kg GAA resulted in a reduction of feed consumption and consequently of weight gain (P ≤ 0.05). Feed conversion was not affected and was 1.48 to 1.49 in all treatments. Increasing levels of dietary GAA gradually increased the creatine concentration in breast muscle and liver tissues (P ≤ 0.05) indicating a transformation and retention of dietary GAA as creatine. In experiment 2 the non-supplemented basal diet allowed us to determine the endogenous GAA, creatine, and creatinine excretions. Accordingly, only small amounts of these metabolites were recovered in feces while they were much higher in urine. Increasing dietary GAA intake increased fecal and renal GAA, creatine, and creatinine excretion and was significant (P ≤ 0.05) at 6.0 g/kg dietary GAA compared to no or 0.6 g/kg GAA supplementation. The mean true fecal digestibility of GAA (99%) was unaffected by the level of supplemental GAA. Considering renal GAA excretions, true availability of supplemental GAA was reduced with increasing dose (83% vs. 71%; P ≤ 0.05). Taking into account creatine and creatinine excretions above those of the basal diet, as they are a consequence of increasing dietary supply, true availability of supplemental GAA shrank from 76% (0.6 g/kg GAA) to 46% (6.0 g/kg GAA; P ≤ 0.05). Changes in blood creatine and creatinine levels reflected the changes observed in the liver and muscle tissues and may suggest increased transport to excretion organs. Data from these experiment were used to estimate the creatine requirement.

Effect of different levels of mannan-oligosaccharide supplementation on the apparent ileal digestibility of nutrients, N-balance and growth performance of weaned piglets.

Several studies report that dietary mannan-oligosaccharides (MOSs) improve the growth performance of piglets, however, only a few studies focus on nutrient digestibility. The aim of the study was to investigate the effect of dietary MOS on ileal digestibility of nutrients and on N-balance and growth performance of piglets weaned at 28 days of age. Three experiments were conducted: a digestibility trial with a total of 30, simple T-cannulated piglets (Exp. 1), a N-balance trial with a total of 48 intact piglets (Exp. 2) and a performance trial with a total of 324 piglets (Exp. 3). In Exp. 1 and 2, the same five dietary treatments were carried out by supplementing the basal diet with 0, 1, 2, 4 g MOS or with 0.2 g antibiotic growth promoter (AGP, Avilamycin) per kg of diet. In Exp. 3, three dietary treatments were used as follows: the basal diet was supplemented no additive, 2 g MOS or 0.2 g AGP (Avilamycin) per kg of diet. Dietary MOS (2 or 4 g/kg) enhanced the ileal digestibility of crude protein similar to antibiotics. Addition of 1 g/kg MOS significantly increased the digestibility of Ca and P by 8.4% and 7.7% units, respectively; however, further increment did not enhance the absorption. Addition of 1 or 2 g/kg MOS significantly increased the ileal digestibility of lysine, methionine, cystine and threonine with the same magnitude or even more than the AGP. In our study, MOS supplementation had no influence on N-balance and growth parameters. Because of the better apparent ileal digestibility of certain nutrients, however, the protein, lysine, methionine, cystine, threonine, Ca and P contents of the diet can probably be reduced without weakening the rearing performance of piglets, when the diet is supplemented with 2 g/kg MOS.