Measurement of true ileal calcium digestibility of feed ingredients for broiler chickens : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Institute of Veterinary, Animal and Biomedical Science (IVABS), Massey University, Palmerston North, New Zealand

Listed in 2017 Dean's List of Exceptional ThesesThe recent interest towards the use of digestible phosphorus (P) in poultry feed formulations necessitates the measurement of true calcium (Ca) digestibility of feed ingredients because of the close relationship between these two minerals for their absorption and post absorptive utilisation. When this thesis research was initiated, no published data were available on Ca digestibility of feed ingredients for broiler chickens. The major objective of the studies reported in this thesis was to determine the true Ca digestibility of feed ingredients for broiler chickens. In total, nine studies were conducted. The first study (Chapter 4) was conducted to determine the effect of methodology on ileal endogenous Ca losses. Three methods, namely feeding a Ca- and P-free diet, maize gluten meal based diet and egg albumen based diet, were used. Ileal endogenous Ca losses differed among different methodologies. The highest ileal endogenous losses of 125 mg/kg dry matter intake (DMI) were recorded on the Ca- and P-free diet, followed by 77 and 43 mg/kg DMI on maize gluten meal and egg albumen diets, respectively. In the second and third studies (Chapters 5 and 6), regression and direct methods, respectively, were used to determine the true Ca digestibility of meat and bone meal (MBM). The true Ca digestibility coefficient of MBM samples were ranged from 0.41 to 0.60. No difference was observed between true Ca digestibility coefficients of MBM determined by regression and direct methods. Since the direct method is less laborious and cost effective compared to regression method, this method was used in subsequent studies (Chapters 7 to 10) to determine the true Ca digestibility of a range of Ca sources. In fourth and fifth studies (Chapters 7 and 8), the influence of dietary P, particle size and Ca to non-phytate P ratio was investigated on the true Ca digestibility of limestone for broiler chickens. The true Ca digestibility of three limestone samples varied from 0.56 to 0.62. Supplementation with recommended dietary P (4.5 g/kg) increased the true Ca digestibility of limestone when compared to diets without P. An increase in particle size from <0.5 to 1-2mm improved the true ileal Ca digestibility of limestone. Widening the Ca to non-phytate P ratio reduced the true Ca digestibility of limestone for broiler chickens. The sixth study (Chapter 9) was conducted to determine the effect of Ca source and particle size on the true Ca digestibility and total tract retention. Limestone and oyster shell were used as Ca sources. No difference was observed between the true Ca digestibility of limestone and oyster shell. An increase in particle size from <0.5 to 1-2 mm increased both the Ca digestibility and retention of both Ca sources, and increased the Ca concentration of gizzard contents. The study reported in Chapter 10 was conducted to determine the true Ca digestibility of dicalcium phosphate (DCP), monocalcium phosphate (MCP), canola meal, poultry by-product meal and fish meal, and to compare the effect of dietary adaptation length on true Ca digestibility of DCP and MCP. The true Ca digestibility coefficients of these feed ingredients were lower than MBM, limestone and oyster shell, and ranged from 0.24 to 0.33. It was speculated that the length of adaption to the assay diets may be responsible for the lower than expected estimates. The effect of dietary adaptation length (24, 48 or 72 hrs) was subsequently examined, but had no effect on true Ca digestibility of DCP and MCP. In the final study (Chapter 11), the true Ca digestibility of DCP was determined using different methodologies (regression, difference and direct methods). The true Ca digestibility coefficients of DCP were 0.34 and 0.21 with direct and different methods, respectively. A very low digestibility coefficient of 0.13 was determined by the regression method. In conclusion, the true Ca digestibility coefficient of major Ca sources (limestone, oyster shell and MBM) is not high and varied from 0.40 to 0.70. Particle size of limestone and oyster shell influenced Ca digestibility, with coarser particles having higher digestibility. The direct method appears to be suitable for the determination of true Ca digestibility of limestone, oyster shell and MBM, but may not be appropriate for other Ca sources with intrinsic imbalance of Ca and P

Digestibility in selected rainbow trout families and modelling of growth from the specific intake of digestible protein

The experiments aimed to clarify variations in digestibility of dietary nutrients in rainbow trout. Furthermore, the objective was to study how differences in digestibility might be related to growth and feed utilisation at various growth rates. When comparing the results from the experiments it appeared that particularly protein digestibility was closely related to specific growth rate and feed conversion ratio at high growth rates. As a tool to visualise the relationship between protein digestibility and growth of rainbow trout a growth model was developed based on the specific intake of digestible protein, and general assumptions on protein content and protein retention efficiency in rainbow trout. The model indicated that increased protein digestibility only partly explained growth increase and that additional factors were important for growth increment

Brown Mid-Rib Corn Variety Trial

Brown mid-rib (BMR) corn has a lower lignin content than other silage corn varieties. The lower lignin content increases the fiber digestibility (NDF digestibility) of the corn silage. Increases in NDF digestibility lead to increased in dry matter intake, milk production, milk protein content, and better body condition. Several studies have reported that for every one percentage point increase in NDF digestibility fed to dairy cattle there will be a 0.50 lb per day increase in milk production. Feeding BMR corn silage is a means to increase NDF digestibility and milk production. Since 2010, the University of Vermont Extension Northwest Crops & Soils program has conducted research trials to evaluate BMR corn silage varieties. In 2012, the trial included 10 varieties from three different seed companies. While the information presented can begin to describe the yield and quality performance of these BMR corn varieties in this region, it is important to note that the data represent results from only one season and one location. Compare other hybrid performance data before making varietal selections

The use of near infrared reflectance spectroscopy (NIRS) for prediction of the nutritive value of barley for growing pigs

peer-reviewedThere is a need in the feed industry for a rapid means of evaluating the nutritive value of feeds and feed ingredients. Chemical analysis provides only basic information and most of the laboratory techniques take too long for this information to be of use in feed formulation at the feed mill. Near infrared reflectance spectroscopy (NIRS) has been proposed as an alternative means of predicting nutritive value. In this study, NIRS was used to predict the digestible energy (DE) concentration and in vitro ileal digestibility of crude protein (CP) and total-tract digestibility of energy of locally produced barley. The calibration and validation statistics were developed using modified partial least squares (MPLS). Derivatisation and scatter correction procedures were carried out to reduce interference from external effects. The correlations between actual and predicted DE values, based on both calibration (R2 0.93) and validation (R2 0.69), were strong with corresponding low standard errors of calibration (SEC) and cross validation (SECV) (SEC 0.128, SECV 0.279). Strong correlations were also observed between predicted and actual in vitro digestibility values for both calibration and validation exercises. It was noted that validation weakened the correlations (R2 0.73 vs. 0.50 for in vitro ileal digestibility of CP and 0.80 vs. 0.68 for in vitro total tract digestibility of energy) and fractionally increased the standard errors (0.016 vs. 0.020 for in vitro ileal digestibility of CP and 0.018 vs. 0.024 for in vitro total tract digestibility of energy). The correlations obtained by cross validation of the lowest SECV equations were not significantly different to those obtained by the scatter correction treatments. The strong relationships and low standard errors obtained between the actual and predicted values indicates that NIRS may be of use in predicting the nutritive value of barley for growing pigs, although more research is required to include larger sample sets

Influence of oxidized oils on digestibility of caseins in O/W emulsions

The impact of lipid oxidation on protein modifications in emulsions and the consequences on protein digestibility remains unclear. In this study, this impact is evaluated in casein (6 mg mL(-1)) based emulsions containing oxidized soybean or fish oil (3%) in presence (0.3%) or absence of the emulsifier Tween 20. Emulsions are prepared using oils at three oxidation levels and subsequently the impact on protein digestibility is evaluated after 24 h incubation at 4 degrees C. Remarkably, protein digestibility increases in emulsions containing medium and highly oxidized fish oil: 70 +/- 0.4% and 73 +/- 0.4% of the proteins are digested, respectively, whereas protein digestibility in emulsions containing low oxidized fish oil amounted to 63 +/- 0.4%. Protein digestibility in emulsions containing soybean oil stabilized by Tween 20 is not influenced by the oxidation level of the oil used. A remarkable tendency is observed for the malondialdehyde content of the emulsions depending on the presence of Tween 20. For soybean oil based emulsions, malondialdehyde concentrations are consistently higher in the presence of Tween 20. On the other hand, for the fish oil based emulsions an opposite trend is observed, except at the highest oxidation level evaluated, for which no significant differences can be detected. It is concluded that the composition of the interface in emulsions depends strongly upon the degree of oil oxidation and the presence of other emulsifiers. If the oil is more oxidized, less protein is present in the interface restricting the impact of lipid oxidation products on the proteins and hence their digestibility

Phosphorus in pig diets

Pig feed is mainly based on cereals where phosphorus (P) is mostly present in inositol hexaphosphate (IP6), which is not readily available to monogastric animals. More available P sources are often added to ensure that pigs’ requirements are fulfilled; this results in high excretion levels of P. The digestibility of P depends on phytase activity and amount of IP6 in feedstuffs. The overall aim was to study effects of liquid feeding, P levels and phytase supplementation on digestibility and performance. Effects of soaking and P levels on digestibility were studied by total collection in metabolic cages, and effects on performance were studied in 192 growing pigs. Effects of soaking fermentation and phytase supplementation on ileal and total tract digestibility were studied with indicator technique on pigs surgically fitted with PVTC cannulas. P levels and phytase supplementation were studied in 104 pregnant sows for two reproduction cycles. All diets were cereal based and included wheat. Basic properties of a cereal mix fermented with whey, wet wheat distillers’ grain and water in different temperatures were also studied. Soaking reduced the level of IP6, whereas apparent digestibility of P was not significantly improved. Soaking increased average daily weight gain, carcass weights and improved the energy conversion ratio in pigs fed a low P diet to the same level as pigs fed high P diets. Low P diets resulted in lower femur density than high P diets. However, soaking of a low P diet resulted in increased femur density. Fermentation degraded IP6 efficiently and improved ileal apparent digestibility of P, organic matter, nitrogen, amino acids and total tract apparent digestibility of organic matter. Microbiological and biochemical properties of fermented liquid diets are strongly affected by feed components and temperature used. Phytase supplementation slightly affected apparent digestibility of P. Supplementing a low P gestation diet with phytase did not significantly affect sow performance. The slight effects of phytase supplementations found may depend on high levels of intrinsic phytase in the diets, and possibly suggest that the provided P level in the sows may have been sufficient. Under typical Swedish conditions of sow management, reduced total P level in gestation diets seems not to negatively affect performance

Factors affecting sorghum protein digestibility

In the semi-arid tropics worldwide, sorghum (Sorghum bicolor (L.) Moench) is cultivated by farmers on a subsistence level and consumed as food by humans. A nutritional limitation to its use is the poor digestibility of sorghum protein when wet cooked. The factors affecting wet cooked sorghum protein digestibility may be categorised into two main groups: exogenous factors (grain organisational structure, polyphenols, phytic acid, starch and non-starch polysaccharides) and endogenous factors (disulphide and non-disulphide crosslinking, kafirin hydrophobicity and changes in protein secondary structure). All these factors have been shown to influence sorghum protein digestibility. More than one factor may be at play at any time depending on the nature or the state in which the sorghum grain is; that is whether whole grain, endosperm, protein body preparation, high-tannin or condensed-tannin-free. It is proposed that protein crosslinking may be the greatest factor that influences sorghum protein digestibility. This may be between ?- and ß-kafirin proteins at the protein body periphery, which may impede digestion of the centrally located major storage protein, a-kafirin, or between ?- or ß-kafirin and a-kafiri

Effects of organic plant oils and role of oxidation on nutrient utilization in juvenile rainbow trout (Oncorhynchus mykiss)

The study compared the effect of four either fresh or force oxidized organic plant oils in diets for juvenile rainbow trout (Oncorhynchus mykiss) in which 47% of conventional LT fish meal protein was substituted by a mixture of 3 organic plant protein concentrates. Fish oil was completely substituted with either organic linseed oil; rape seed oil; sunflower oil or grape seed oil and evaluated based on feed intake, feed utilization, growth and digestibility. None of the plant oils affected feed intake and growth parameters. Organic plant oils had all a positive effect on lipid digestibility as compared with the fish oil based control diet, despite the very different FA profiles. The organic vegetable oils did not undergo autoxidation, as opposed to the fish oil control for which lipid digestibility was significantly negative influenced

The Effects of Different Energy and Protein Ratio to Goat’s Nutrient Intake and Digestibility

The objective of this research was to study the effects of different energy and protein ratio towards goat’s nutrient intake and digestibility. Twenty four male goats, 6 – 7 months old with initial average live weight 13+1.56 kg, coefficient variant11.78%) were used in this research. The complete feed ration which consisted of King Grass (Pennisetum purpureum), soybean powder, rice bran, dried cassava and molasses was used in this research. Protein content on each component was 10, 12 and 14% and total digestible nutrients (TDN) 60 and 65%, respectively. Dry matter (DM) and organic matter (OM) intake, DM and OM digestibility were studied in this research. Analysis of variance (ANOVA) was employed to analyze the data. Test of Small Difference (P0.05) among crude protein and TDN treatments. Different energy and protein ration treatments caused different DM and OM intake but were not cause different in DM and OM digestibility. Based on the research results, a study on the effects of different ration’s energy and protein ratio towards N efficiency should be conducted in order to increase cattle productivity