2. Food consumption and egg production decreased as dietary calcium decreased. Shell weight was unaffected on diets 1 and 2; on diet 3 there was slight reduction of shell weight and on diets 4 to 8 the reduction was marked. The proportion of calcium in the shell was affected particularly on diets 7 and 8, though those from diet 5 also showed a decreased shell calcium.
3. The values for calcium intake and calcium loss in the egg showed that, generally, birds restricted calcium loss to less than intake. Only on the very low concentrations of calcium (diets 6, 7 and 8) did output appear to exceed input.
4. The main mechanism for controlling calcium loss involves the regulation of the number of eggs produced, i.e. the number of ovulations. Alterations in shell quality are of less importance with respect to calcium balance, although shell strength was impaired on the more restrictive diets (5 to 8). 相似文献
2. liver weight and lipid content in birds fed the 2 and 4 g γ‐linolenic acid/kg diet were significantly lower than those in birds fed the γ‐linolenic acid‐free diet. However, no significant difference was observed between the γ‐linolenic acid‐ and linoleic acid‐supplemented diets.
3. In birds fed the 4 g γ‐linolenic acid/kg diet, the proportion of arachidonic acid in the liver lipid was similar to that in quail fed the 20 g linoleic acid/kg diet, implying a conversion rate from linoleic acid to y‐linolenic acid of approximately 20% of whole body content.
4. It is concluded that linoleic acid itself is not essential for Japanese quail and that at least 2 g/kg of γ‐linolenic acid in the diet completely prevents liver enlargement accompanied by lipid accumulation. 相似文献
2. In experiment 1, 5 graded amounts of a DL‐methionine and L‐cysteine (1:1 by weight) mixture were added to basal diets containing 197 or 233 g crude protein/kg. The diets containing 197 g protein/kg were fed with or without the further addition of 36 g crude protein/kg from nonessential amino acids. The amino acid balance of all diets was kept constant for all essential amino acids except the SAA. In experiment 2, 5 graded amounts of SAA from either a crystalline source (DL‐methionine or a mixture of DL‐methionine and L‐cysteine) or from intact proteins were added to a diet containing 208 g protein/kg.
3. At each protein concentration there were significant responses to the SAA addition in weight gain, food conversion efficiency, and carcase quality. Non‐linear exponential regression analyses were used to describe bird responses to SAA concentration. The broiler chick's requirement for SAA increased with increasing dietary protein concentrations ranging from 197 to 259 g protein/kg.
4. The utilisation of SAA differed also with differences in origin (crystalline or peptide‐bound), and methionine:cysteine balances. Compared to DL‐methionine, a 1:1 mixture of DL‐methionine and L‐cysteine was only 81% or 86% as effective in supporting growth or food conversion, respectively. SAA from added protein was even less effectively utilised.
5. The addition of nonessential amino acids tended to decrease food intake without affecting SAA utilisation.
6. Slaughter yield and breast meat yield were clearly increased while fat deposition was clearly decreased, by SAA addition. The response in breast meat yield suggested an important economic benefit for further meat processing. Nitrogen retention was significantly enhanced by SAA supplementation from crystalline sources, and this led to reductions of up to 30% in the amount of nitrogen excreted per kg weight gain. 相似文献
2. In hens receiving a normal diet containing a calcium supplement in a powdery form Pi increased from 25 to 42 mg/1 during an entire shell formation cycle (from 10 to 22 h after oviposition of the previous egg), while in cockerels Pi decreased slightly during the night.
3. This increase in Pi in hens, was not related to cessation of feeding at the onset of darkness but was specifically connected with the beginning of shell secretion.
4. When hens received calcium as crushed sea‐shells separately from the diet, the nocturnal peak in Pi virtually disappeared and only a temporary increase of 4 mg/1 between 10 and 14 h after oviposition remained.
5. These results indicate that the beginning of shell secretion is always accompanied by an increase in Pi and that a separate presentation of dietary calcium reduces the bone mobilisation at night. 相似文献
2. In experiment 1, replacing 75 μg cholecalciferol/kg with the same weight of 25‐HCC decreased significantly (P<0.01) the incidence of TD from 65 to 10%.
3. In experiment 2, the incidence of TD in the control group was lower, but feeding amounts of 25‐HCC up to 250 μg/kg had a linear effect on the incidence of TD that was significant at P=0.06. There was no effect or interactions with dietary addition of 250 mg ascorbic acid/kg. Dietary addition of 5 μg 1‐HCC/kg decreased TD incidence from 21 to 5%, though the effect was not significant (P>0.1).
4. TD incidence in experiment 3 was too low to determine an effect of 25‐HCC or 1,25‐DHCC on TD incidence, though in this, as in both other experiments, the severities of TD lesions were always lower with diets containing cholecalciferol metabolites.
5. Hypercalcaemia was not observed after feeding up to 250 μg 25‐HCC/kg in either experiments 2 or 3.
6. It is concluded that 25‐HCC may be an effective practical means of improving broiler leg health by alleviating the incidence and severity of TD. 相似文献
2. The dietary treatments had no significant effect upon food intake, egg output, shell thickness, shell deformation or specific gravity of the eggs.
3. The 28‐h cycle reduced mean rate of lay by 4.5%, increased egg weight by 5.8% and increased shell thickness by 9.4%. The proportion of eggs with shell faults revealed on candling was reduced from 4.1 % to 2.8%.
4. It is concluded from this and other sources that decreasing dietary phosphorus or modifying vitamin D supplements may sometimes lead to increases in shell thickness of the order of 1 to 2%, but that these changes are unlikely to result in a measurable reduction in the proportion of cracked eggs late in the laying year.
5. A 28‐h light‐dark cycle results in a longer and more uniform interval between consecutive ovipositions and thus gives reliable increases in shell thickness which are large enough to reduce the proportion of cracked eggs in many practical situations. Whether it is profitable to use an ahemeral cycle will depend upon the relative prices paid for eggs of different sizes. 相似文献
Background
Gastric ulceration is highly prevalent in horses, and there is a large commercial market for feed-additives and non-licenced products that claim effect for prevention and treatment of gastric ulceration. ImproWin® has been used as a feed additive in horses with anecdotal evidence that it may have some positive effects on gastric ulceration.The aim of this study was to investigate the effect of ImproWin® treatment on spontaneously occurring gastric ulcers of the squamous mucosa in Standardbred and Coldblooded trotting racehorses.The study was performed as a randomised, double-blinded, single centre study with stratified semi cross-over design with breed as stratification factors. The horses were clinically and endoscopically examined prior to start and after three weeks of treatment. The ulcerations were scored in accordance with Equine Gastric Ulcer Council (EGUC) recommendations on a 5 point scale and on a 10 cm Visual Analogue Scale (VAS). The patients were responder-classified after 3 weeks. Responders in need of ulcer treatment were randomly allocated to 2 or 4 weeks of additional treatment. Non-responders to placebo were crossed to ImproWin®.Results
The 5-point EGUC score and VAS recorded score was significantly reduced (P ≤ 0.01) in both groups after 3 weeks of treatment. From 3 weeks to the end of treatment the score was further significantly reduced in the ImproWin® group (P ≤ 0.05).At the end of treatment, 78% in the ImproWin® group and 54.8% in the placebo group were classified as responders. The difference was significant (P = 0.04).Conclusions
ImproWin® may aid the healing process of ulcers of the gastric squamous mucosa of trotters. 相似文献2. Supplementation of ascorbic acid, α‐tocopherol, or a low level of L‐cysteine (3 g/kg) did not significantly affect any of the hepatic variables evaluated. Hepatic glutathione was not increased by the supplementation of dietary L‐cysteine.
3. L‐cysteine supplemented at a level of 6 g/kg decreased hepatic dry matter and fat contents without affecting the hepatic malondialdehyde or the liver haemorrhagic score.
4. Because one of the predisposing factors of FLHS is a high hepatic fat content it was concluded that dietary supplementation of L‐cysteine (6 g/kg) may be useful in the prevention of the disease. 相似文献
2. Some of these embryos were injected with primordial germ cells (PGCs) after 55 h of incubation to attempt to repopulate the gonads.
3. Primordial germ cells transfected with a defective retrovirus containing the reporter gene lac Z were shown to settle in these sterilised gonads.
4. Quantitative histology of 6‐d embryos showed that busulphan produced 75% sterilisation but that PGCs could repopulate these gonads.
5. The technique of producing such germ line chimaeras is of value in studying cell kinetics, gonad differentiation and the production of transgenics. 相似文献
2. Adding 5 μg 1,25‐DHCC/kg to a diet containing 12 g calcium/kg was more effective than early food restriction or meal feeding in preventing leg abnormalities but was found to cause a growth depression.
3. The second experiment, which had a factorial design, with diets containing 7.5, 100 and 12.5 g calcium and 0, 2.0, 3.5 and 5.0 μg 1,25‐DHCC/kg, showed linear and quadratic interactions between these dietary factors. Diets with higher concentrations of both 1,25‐DHCC and calcium resulted in growth depression associated with hypercalcaemia.
4. The incidence of tibial dyschondroplasia (TD) at 3 weeks of age was highest with the basal diet containing 7.5 g calcium/kg and was markedly reduced by addition of 1,25‐DHCC and/or calcium. The incidence was very low or non‐existent when 1,25‐DHCC was fed at 3–5 μg/kg or greater.
5. Feeding 5 μg/kg 1,25‐DHCC had no effect on plasma 1,25‐DHCC concentrations, although at the higher dietary calcium contents plasma concentrations of 25‐hydroxy‐ and 24,25‐dihydroxy‐cholecalciferol were lower in those birds fed 1,25‐DHCC.
6. It is concluded that 1,25‐DHCC is most effective in preventing TD without accompanying growth depression when it is fed in conjunction with diets containing less than 10 g calcium/kg. 相似文献
2. Fat type had no consistent effect on yolk carotenoid content but yolk α‐tocopherol concentrations were lower with the soyabean oil diet.
3. Yolk concentrations of all carotenoids measured and yolk colour were unaffected by dietary α‐tocopherol concentration. 相似文献
2. In this experiment, carcase analyses of each of three breeds of pullets were conducted at weekly intervals throughout the growth of the pullets, to 18 weeks of age. Measurements were made of body weight, gut‐fill and feather weight, and chemical analyses consisted of water, protein, lipid and ash measurements of both the body and the feathers. Each age group comprised 10 birds of each breed.
3. Gompertz functions accurately estimated the growth of both body protein and feather protein, to 18 weeks of age, from which the rate of growth of these two components of the body could be estimated. The mature weight of pullets was overestimated by the Gompertz growth curve, which may indicate that a pullet ceases to increase in body protein content once sexual maturity has been reached.
4. Using allometric relationships between the chemical components of the body and of feathers, all the components of growth could be estimated from the growth of body protein and feather protein. These components were then added together to determine the growth rate of the body as a whole.
5. The daily amino acid requirements for 4 functions were calculated, namely, those for the maintenance of body protein and feather protein, and for the gain in body protein and feather protein. These requirements were then summed to determine the requirement of pullets on each day of the growing period.
6. Using the ‘effective energy’ system, the amount of energy required by these pullets was calculated for each day of the growing period, from which the desired daily food intake of the pullets could be predicted. By dividing the amino acid requirement by this daily food intake it was possible to determine the concentration of amino acids that would be needed in the diet in order to meet the requirements of a pullet.
7. The results indicate that the ratio between the requirement for lysine and for methionine and cysteine changes dramatically during the growing period, negating the concept of a fixed ratio between all the amino acids during growth.
8. The above process is the first step in determining the optimal feeding programme for a population of pullets of a given genotype. The constraining effects, of the diet being offered and of the environment in which the pullets are housed, on the food intake and growth rate of each pullet have to be estimated, and such a theory can then be expanded to include all the individuals in the population. Only by the use: of simulation models can all these constraining effects be considered simultaneously. 相似文献