The efficiency of lactation (including milk composition and milk yield) in the sow, and the environment of the piglet is taken into consideration in an attempt to maximise sow performance and improve piglet survival and growth. In many commercial intensive piggeries, the sow suckles up to 12 piglets for about three and a half weeks. During this time, the piglets' major source of nutrition is sows' milk, often supplemented with 'creep food' and electrolyte solutions. However, in some piggeries, there is a tendency towards early segregated weaning. Piglets are removed from the sow often in the second week of lactation, and placed in a new location and fed a diet modelled primarily on the composition of cows' milk. This type of artificial rearing may increase piglet performance by minimising death by infection, but it can reduce sow performance by compromising her return to oestrus.

Thesis (Ph. D.)--Iowa University. / Cover title. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1963. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 48-51).

Cartas al editor

The studies recorded in this thesis cover a wide portion of the field of creatine-creatinine metabolism. They involve a consideration of the problem of the origin of creatine, of the endocrine factors controlling its metabolism, and of the function of creatine and creatinine in the body. In order to obtain a true perspective of the place of these investigations in relation to the physiology of creatine as a whole, it is first necessary to review briefly what is known of the metabolism and function of the two substances. And, in view of the light they throw on these questions, consideration must also be given to the chemical constitution and distribution of creatine and creatinine.

Oral creatine supplementation has been shown to increase skeletal muscle total creatine (TCr) content, and in some cases improve performance in high-intensity short duration exercise. A variety of factors related to an enhanced efficacy of adenine nucleotide metabolism have been demonstrated as partly responsible for this ergogenic effect. Also, there is evidence that high-intensity sprint training results in a decrease in muscle total adenine nucleotide (TAN) and/or ATP stores. This placebo controlled double-blind study examined whether an oral creatine supplementation regimen would 1) increase muscle TCr content, 2) attenuate any loss in TAN or ATP during intermittent sprint training, and 3) have an ergogenic effect on performance after sprint training. Thirteen male endurance trained cyclists ingested 20 g of creatine monohydrate supplement or placebo per day for 7 days, after which they ingested a maintenance dose of 2 g creatine or placebo per day for the remainder of the trial (15d). While on the maintenance dose, subjects performed intermittent sprint training (ST) on a cycle ergometer (10 x 10 s sprints with 140 s active recovery) for 6 consecutive days and a 7th day after one day of rest. Performance tests were performed before and after ST, and metabolic tests were performed on the 1st and 7th day of ST. TCr increased significantly with creatine supplementation (creatine group pre: 121 ± 4, post: 147 ± 9; vs. placebo group pre: 122 ± 4, post: 125 ± 4 mmol/kg dm; mean± SEM; p<0.05). The increase in TCr correlated with the percentage Type IIB fibres (r=0.95, p<0.005). By day 7 of ST, TCr content was no longer significantly higher than pre-supplementation levels despite the maintenance dose of creatine. ST resulted in a significant decrease in resting muscle TAN and ATP content in both groups (ATP content in creatine group pre: 24.1 ± 0.8, post: 17.2 ± 0.5; and placebo group pre: 26.5 ± 1.1, post: 18.0 ± 0.6 mmol/kg dm; p<0.001). During and in recovery from ST on day 7, both groups had lower plasma ammonia (p<0.05), hypoxanthine (p<0.001) and urate (p<0.001) accumulation than on day 1 of ST. There was no improvement in 1-hr cycle distance performance after ST, but peak sustained power output increased in the creatine group and not in the placebo group after ST (p<0.05). Peak and mean power during a 30 s Wingate test increased significantly (p<0.05) after ST but there was no additional ergogenic effect of creatine supplementation. In conclusion, this study shows that 1) the efficacy of muscle creatine uptake was dependent on the percentage of Type IIB fibres, 2) creatine supplementation and maintenance (2 g/d) did not attenuate ATP or TAN loss during 7 days of ST, 3) ST decreased the accumulation of plasma products of adenine nucleotide degradation and improved 30 s sprint performance, and 4) creatine supplementation and ST did not improve I-hr cycle distance performance.

No description available.

Little is known about the anti-inflammatory activity of creatine. The aim of this study was to evaluate the anti-inflammatory effects of creatine supplements in canine chondrocytes (CnC). CnC were stimulated with IL-1β. Release of PGE2 and TNFa was measured using ELISA. Changes in oxylipin profile was assessed using HPLC/MS. Expression of COX-2 and phosphorylated NF-kB was performed using western blot. Changes in above inflammatory responses were examined following treatment with various creatine compounds including the metabolite creatinine. COX inhibitor, Rimadyl, substantially reduced PGE2 release, despite increasing both TNFa release and COX-2 expression. All creatine compounds, including creatinine, reduced PGE2, COX-2 and TNFa in stimulated CnC. In addition, all the compounds examined reduced phosphorylated NF-kB expression. The creatine compounds were also able to interfere with the production of several oxylipins in response to IL-1β. Creatine supplements may have a beneficial role in preventing inflammation within the joint and other tissues. / May 2016

Homocysteine (Hcy) is metabolized through a series of remethylation and transsulphuration processes that require the co-factors vitamins B6, folate (the nutrient derived from food, and folic acid is supplemental), and B12. Homocysteine metabolism results in the production of creatine (Cr). By way of negative feedback creatine supplements could potentially decrease Hcy production. Low dietary intake of vitamins and creatine, often a consequence of a vegetarian diet may also increase serum Hcy concentrations. It was therefore the purpose of this study to examine the effect of a five day creatine loading period (0.25 g Cr/kg lean body mass (LBM)/day) in female vegetarians (VG) (n=9, age 25 ± 3.6) and non-vegetarians (NV) (n=11, age 24 ± 5.9) on serum levels of Hcy, vitamins B6 and B12, whole blood folate, and on a number of fitness measures known to be positively affected by creatine supplementation: peak torque and average power during leg extensions; one repetition maximum (1RM) bench and leg press; peak power during repeated Wingate anaerobic tests. Aside from a difference in change scores for leg press, there were no differences between dietary groups for the fitness measures, and therefore the participants were pooled for comparisons between time points. Urinary creatine was significantly greater following the five day loading period (81 ± 113 vs. 647 ± 421 µmol). In contrast, urinary creatinine did not change. A significant increase in plasma vitamin B6 (pyridoxal 5-phosphate) was found (72 ± 24 vs. 94 ± 24 nmol/L) (p < 0.05), although there were no between group differences. Serum Hcy, vitamin B12, and whole blood folate levels did not change significantly over time in either group. Participants showed significant increases post-loading in bench press (45 ± 13 vs. 48 ± 12 kg.) and leg press (116 ± 35 vs. 125 ± 40 kg) (p < 0.05). Changes scores for leg press were greater for the vegetarian participants when compared with non-vegetarians (16 ± 16 vs. 3 ± 9 kg). Significant improvements post-loading were also noted for peak torque (85.0 ± 15.0 vs. 91.8 ± 12.9 Nm) and average power (99.5 ± 14.4 vs. 107.1 ± 14.8 W) (p < 0.05). Peak power during repeated Wingate anaerobic tests also significantly improved in response to the intervention (449.2 ± 92.6 vs. 472.4 ± 103.5 W) (p < 0.05). This response did not differ however between the two diet groups. These results suggest that a five day creatine loading protocol similarly affects fitness performance measures in both vegetarians and non-vegetarians. There was no significant effect of the supplementation protocol on serum Hcy concentration, suggesting that the supplemented creatine did not decrease the reformation of Hcy, as originally hypothesized.

Homocysteine (Hcy) is metabolized through a series of remethylation and transsulphuration processes that require the co-factors vitamins B6, folate (the nutrient derived from food, and folic acid is supplemental), and B12. Homocysteine metabolism results in the production of creatine (Cr). By way of negative feedback creatine supplements could potentially decrease Hcy production. Low dietary intake of vitamins and creatine, often a consequence of a vegetarian diet may also increase serum Hcy concentrations. It was therefore the purpose of this study to examine the effect of a five day creatine loading period (0.25 g Cr/kg lean body mass (LBM)/day) in female vegetarians (VG) (n=9, age 25 ± 3.6) and non-vegetarians (NV) (n=11, age 24 ± 5.9) on serum levels of Hcy, vitamins B6 and B12, whole blood folate, and on a number of fitness measures known to be positively affected by creatine supplementation: peak torque and average power during leg extensions; one repetition maximum (1RM) bench and leg press; peak power during repeated Wingate anaerobic tests. Aside from a difference in change scores for leg press, there were no differences between dietary groups for the fitness measures, and therefore the participants were pooled for comparisons between time points. Urinary creatine was significantly greater following the five day loading period (81 ± 113 vs. 647 ± 421 µmol). In contrast, urinary creatinine did not change. A significant increase in plasma vitamin B6 (pyridoxal 5-phosphate) was found (72 ± 24 vs. 94 ± 24 nmol/L) (p < 0.05), although there were no between group differences. Serum Hcy, vitamin B12, and whole blood folate levels did not change significantly over time in either group. Participants showed significant increases post-loading in bench press (45 ± 13 vs. 48 ± 12 kg.) and leg press (116 ± 35 vs. 125 ± 40 kg) (p < 0.05). Changes scores for leg press were greater for the vegetarian participants when compared with non-vegetarians (16 ± 16 vs. 3 ± 9 kg). Significant improvements post-loading were also noted for peak torque (85.0 ± 15.0 vs. 91.8 ± 12.9 Nm) and average power (99.5 ± 14.4 vs. 107.1 ± 14.8 W) (p < 0.05). Peak power during repeated Wingate anaerobic tests also significantly improved in response to the intervention (449.2 ± 92.6 vs. 472.4 ± 103.5 W) (p < 0.05). This response did not differ however between the two diet groups. These results suggest that a five day creatine loading protocol similarly affects fitness performance measures in both vegetarians and non-vegetarians. There was no significant effect of the supplementation protocol on serum Hcy concentration, suggesting that the supplemented creatine did not decrease the reformation of Hcy, as originally hypothesized.