Browsing by Subject "Animal nutrition"

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Effects of a reduction of dietary levels of calcium and phosphorus on performance, bone minerals and mineral excretion of turkey breeder hens in the rearing and laying period
(2023) Gickel, Julia Maria; Rodehutscord, Markus
Phosphorus (P) is an essential mineral in feed for livestock and has finite resources all over the world. The aim of this study was to obtain an idea about the reduction potential of P in the diets of turkey breeders. As the metabolism of P is interlinked with the metabolism of calcium (Ca), Ca was also examined. Therefore, the requirements of P and Ca were studied using a factorial approach. As data about the requirements of these minerals in turkey breeders is limited, the present study mostly used data from other poultry species. Thus, this study can be viewed as an approach to building new resilient data for turkey breeder hens. The results of the factorial approach were embedded in a feeding program for turkey breeder hens during rearing and laying with two different treatments. One group was fed a standard feed (practical diet used before the trial), while the other group was fed a Ca/P reduced feed. In total, four trials were conducted: trials I and III focused on the rearing period while trials II and IV focused on the laying period. All trials were observed independently but the hens from trial I were used also in trial II afterwards for studying long-term effects. In each trial, body weight and feed intake were measured throughout the trial period. Bone mineralization was studied in trial I, including analyses of bone ash as well as Ca and P in the bone ash from the tibia of fallen and culled animals. The egg components were studied in eggs from trial II, including analyses of the percentages of albumen, egg yolk, and egg shell; Ca in albumen; P in albumen; Ca in egg yolk; P in egg yolk; water in egg shell; Ca in egg shell; and P in egg shell. In trials II and IV, laying performance, egg weights, number (and causes) of culled eggs, fertility, hatchability, as well as body weight and fitness of the hatchlings were additionally observed. At the end of each trial, the concentrations of dry matter, Ca, and P in manure were analyzed and a nutrient balance was calculated to classify the results. Body weight development exhibited significant differences between the treatments in eight out of 30 weeks in trial I (five weeks had a higher mean weight in the group with standard feed; three weeks had a higher mean weight in the group with Ca/P reduced feed); three out of 28 weeks in trial II (two weeks had a higher mean weight in group with Ca/P reduced feed; one week had a higher mean weight in the group with standard feed); four out of 30 weeks in trial III (higher mean weight in the group with Ca/P reduced feed); and two weeks out of 28 in trial IV (higher mean weight in the group with Ca/P reduced feed). The feed intake data also fluctuated, with three out of 30 weeks exhibiting a significant difference in trial I (higher mean feed intake in the group with Ca/P reduced feed) and one week with a significant difference in trial II (higher mean feed intake in the group with standard feed). The observations throughout all of the trials revealed the tendency for a higher mean feed intake in the groups with Ca/P reduced feed. A significant difference concerning bone mineralization was not observed. Moreover, the results of laying performance, fertility, and hatchability exhibited no differences between the treatments. Regarding the egg weight in trial II, there were eight weeks with a significant difference between the treatments (seven weeks with a higher mean egg weight in the group with standard feed; one week with a higher mean egg weight in the group with Ca/P reduced feed). In trial IV, only one week exhibited a significant difference between the treatments (higher mean egg weight in the group with Ca/P reduced feed). Regarding the weight of hatchlings in trial II, three weeks had a significant difference between the groups (higher mean weight in the group with standard feed). In trial IV, no significant difference was observed for any week all throughout the trial period. The analyses of egg components revealed significant differences between the treatments according to the percentages of albumen and egg yolk and the calculated value of total Ca in the egg (including the shell). In trials I and III, significant differences existed between the treatments in the concentration of Ca in manure, with a lower level in the group with Ca/P reduced feed. This study concluded that a reduction in the dietary levels of Ca from 1.00–1.10% to 0.56–0.80% and of P from 0.48–0.61% to 0.35–0.50% (av. P) or 0.70–0.80% to 0.50–0.60% (total P) in rearing and a reduction of the dietary levels of Ca from 2.90% to 2.80% or 2.60% and of P from 0.36% to 0.30% or 0.24% (av. P) or from 0.65% to 0.50% (total P) in laying in the feed of turkey breeder hens are possible and did not result in disadvantages. As the present study also compared the results with required recommendations and target levels from breeding companies, it was also able to conclude that these levels are obsolete and should be adjusted downwards.
Effects of diets with different phosporus availability on the intestinal microbiota of chickens and pigs
(2019) Tilocca, Bruno; Seifert, Jana
In the research works of the present thesis, 16S rRNA gene sequencing and metaproteomics were employed to investigate the gut microbiota of chickens and pigs kept at experimental diets with varying amount of calcium-phosphorus (CaP) and supplemented MP. This represents a valuable approach to investigate the bacterial specimens involved in the P absorption, allowing for a comprehensive understanding of how the intestinal bacteria adapt to a new diet and which metabolic routes are affected by changing levels of supplemented P and/or MP. Two major experimental trials were performed during the investigation. The first one was conducted on chickens operating a modulation in the dietary levels of Ca, P and MP. This trial highlighted a shift in the composition of the crop and ceca-associated microbial community depending on the composition of the diet fed. Also, investigated protein inventory revealed that the stress condition due to the reduced P availability is mirrored in the gastrointestinal tract (GIT)-associated microbiota. Marked differences were observed in the functions of the bacterial community in the case of P-available diets versus P-deficient ones. Protein repertoire of the first case draws a thriving microbial community focused on complex and anabolic functions. Contrariwise, the bacterial community in the case of P-lacking diets appears to deal with catabolic functions and stress response. The second trial was conducted on pigs and attempts to define the dynamics featuring the microbiota adaptation to a new challenging diet composed of different protein sources and varying levels of Ca and P. Statistical evidences reveal a stepwise adaptation of the fecal microbiota to the experimental diets fed. Both DNA-based approach and metaproteomics independently reveal three main adaptation phases: -before the feeding of the experimental trial (i.e. Zero), -the response of the microbial community to the challenging factor (i.e. MA) and, finally, - the newly achieved homeostatic balance (i.e. EQ). As observed in the first trial, feeding of the experimental diets impairs the overall fecal microbiota composition, stimulating the presence of phase-specific bacterial specimens and a characteristic relative abundance of the shared ones. Bacterial families responsible for the phase-specific architecture of the fecal microbiota are also active in the biochemical pathways driving the functional peculiarities of each adaptation phase. A deeper investigation of the identified protein repertoire revealed that the observed statistical differences among the adaptation phases are uniquely due to the Ca and P composition of the diets fed. None of the observed effects can be attributed to the diverse protein sources supplemented with the diets. Functional categorization of the identified protein inventory depicts three diverse functional assets of the microbial community. Specifically, prior the feeding of the experimental diets, bacteria are hypothesized to live under homeostatic condition, since they appear to be involved in complex and highly-specialized functions. Following the administration of the experimental diets microbial community changes its functional priority and reduce the expression of highly specialized functions to focus on more essential ones. Proteins involved in complex functions such as widening the substrates array and facing complex sugars tend to increase in abundance while the new homeostatic balance is achieved. Altogether, data from both trials provide useful information for future studies aimed to design effective breeding strategies finalized to reduce the P supplementation in the routinely breeding of livestock and maintain a balanced microbial activity in the animal GIT. Investigation of the dynamics of the porcine microbiota provides instructions on the minimal exposure time required from the intestinal microbiota to adapt to a new dietary composition. This is of fundamental importance for the design of future studies aimed to confirm and/or continue our results. Moreover, the anatomical and physiological similarities occurring between humans and pigs, make our findings of interest for future human nutritional studies, where the mechanisms and lasts of the microbiota adaptation process is still object of discussion.