Effects of Dietary Protein and Lipid Levels on Growth, Body Composition, Blood Biochemistry, Antioxidant Capacity and Ammonia Excretion of European Grayling (Thymallus Thymallus)

Background: This study evaluated growth, body composition, blood biochemistry, antioxidant capacity, innate immunity and ammonia excretion of European grayling (Thymallus thymallus) fed diets containing different protein and lipid contents. Six diets were produced to contain 30, 40 or 50% protein with 10 or 20% lipid and fed to triplicate groups (100 fish per replicate) of fish (25.2 ± 0.28 g) to visual satiety twice daily for 12 weeks. Results: Fish growth was enhanced (P ˂ 0.05) as protein increased from 30 to 40% and plateaued thereafter. Enhancing protein and lipid content of diet led to reduced feed intake and improved feed efficiency. Moreover, protein efficiency ratio increased at higher lipid level while lower values were recorded at higher protein levels. Increasing dietary lipid content led to the enhancement of viscerosomatic index and intraperitoneal fat ratio. An interaction of protein and lipid was found on whole-body lipid, and muscle lipid was responsive to dietary lipid level. Muscle ARA, EPA and Ʃn-6 LC-PUFA contents enhanced by increasing dietary protein level. Moreover, increasing fat content of diet led to enhanced muscle linoleic acid, linolenic acid, ƩMUFA, Ʃn-6, DHA/EPA and n-6/n-3. However, EPA, DHA, Ʃn-6 LC-PUFA, Ʃn-3, Ʃn-3 LC-PUFA and EPA/ARA decreased at higher dietary lipid level. Serum triglyceride (TG) concentration and lactate dehydrogenase (LDH) activity decreased as dietary protein level increased while an opposite effect was observed for cholesterol (CHO) concentration. Increasing fat content of diet led to enhanced serum TG, CHO and glucose concentrations and reduced alanine aminotransferase, aspartate amino transferase and LDH activities. Serum malondialdehyde concentration was enhanced by increasing both dietary protein and lipid contents. Furthermore, serum myeloperoxidase activity was enhanced at higher dietary lipid level. Water total ammonium nitrogen (TAN) concentration was measured after 5 and 24 h of last feeding, and the results indicated the reduction of ammonia excretion as dietary lipid content increased. Conclusions: These findings suggest that 40% dietary protein can support optimal growth of juvenile European grayling and increasing lipid content from 10 to 20% can improve feed utilization and reduce ammonia excretion to the rearing water.

Effect of Dietary Protein Level during Estrus Cycle: Nutrient Digestibility, Quality of Embryo and Pregnancy Rate by Embryo Transfer in Thai Crossbred Goats during Hot Season

Tis study aimed to evaluate the embryo quality and embryo transfer rate of Thai crossbred goats fed different levels of protein in total mixed rations (TMR) during the hot season. Twenty-four non- pregnant Thai crossbred goats with an average body weight of 26±5.9 kg were assigned with a random complete block design (RCBD). Dietary treatments contained 8, 13, and 18 % crude protein (CP) in TMR. The feeding trial lasted for 42 days. Does (female goat) were scheduled to determine embryo quality by surgical laparotomy and flushing. At the end of the feeding trial, the digestion trial was conducted by the total collection method for a 5-day period. The results showed that the average total feed intake and feed conversion ratio did not differ among all treatments (p ˃ 0.05), however, digestible protein intake had increased from 70.39, 79.77 to 89.11 g/d in 8, 13, and 18 % CP group, respectively. Increasing CP levels in TMR resulted in linearly increased goat final body weight (30.25, 28.75, and 32.00 kg), weight gain (3.00, 4.00, and 4.25 kg), and average daily gain (ADG) (87.84, 114.87 and 121.63 g/d). Embryo quality (1, 1, and 3.5 morular follicle state) and pregnancy of embryo transfer rate (25, 25, and 50 %) of the animal received CP level at 8 and 13 % less than that 18 %. These results indicated that dietary protein level during program superovulation regimen affected the good quality of an embryo and the pregnancy rate in an embryo transfer in Thai crossbred goats.

Growth performance and haematological traits of Nigerian local chickens fed varied dietary protein levels

This study was carried out to investigate the growth performance and haematological traits of Nigerian local chickens (NLC) fed varied dietary protein levels. An eleven week feeding trial was done in a 3 x 2 factorial arrangement using six treatment groups comprising a combination of two genotypes of the NLC' identified as normal leather (na) and naked neck (Na) and three dietary protein levels - high protein: HP (22% and 20% CP chick mash and grower mash respectively), medium protein: MP (20% and 18% chick mash and grower mash respectively) and low protein: LP (18% and 16% chick mash and grower mash). Data were collected on growth performance traits (body weight, feed intake, feed conversion ratio and protein efficiency ratio). At the end of the feeding trial a haematological assay was done. Neither genotype nor interaction of genotype and dietary protein level influenced (p>0.05) any of the growth performance traits studied. Birds on HP ate 10.21% and 7.09% less feed than those on MP and LP respectively. A better (p<0.05) protein efficiency ratio (up 10 20.79%) was observed in birds fed LP. Na birds had 4.55% and 17.50x704L-1 more packed cell volume and platelets respectively than na birds (p<0.05). All haematological traits studied, except white blood cell count, showed significant variations (p<0.05) due to varied dietary protein levels. Higher haemoglobin, red blood cell counts, mean corpuscular haemoglobin concentration and platelets were observed in birds fed LP diet. Reducing the dietary protein level had no adverse effect on the NLC thus, the LP diet is recommended for raising the Nigerian local chicken.

Nitrogen balance response to varying levels of dietary protein in slow-growing Windsnyer pigs

Protein requirements for slow-growing pigs have not been defined. The study was designed to determine the relationship between the level of dietary protein and nitrogen balance in slow-growing Windsnyer pigs. Thirty Windsnyer pigs with an initial bodyweight of 34.7 (SD = 0.85) kg were randomly assigned to six experimental diets containing 193, 174, 154, 135, 117, and 97 g/kg of crude protein (CP). Pigs were penned individually. There were five pigs in each diet. The faecal nitrogen output (NFO) showed a decreasing quadratic relationship with protein level. A linear relationship between protein level and urinary nitrogen excretion was observed (P =0.0001). The total nitrogen excreted showed a significant quadratic relationship to decreasing levels of CP in the diets (P =0.0001). The apparent digestibility of nitrogen had a linear relationship with dietary CP level (P =0.0005). A quadratic relationship between dietary protein level and N utilization was observed (P =0.0001). The optimum protein level for total nitrogen excreted, nitrogen utilization and biological value of feed protein were attained at 135 g/kg protein level. The efficiency of nitrogen utilization supports the low protein diet. The present results suggest reducing the dietary protein level for Windsnyer pigs to decrease amount of excreted N that is deposited into the environment.Protein requirements for slow-growing pigs have not been defined. The study was designed to determine the relationship between the level of dietary protein and nitrogen balance in slow-growing Windsnyer pigs. Thirty Windsnyer pigs with an initial bodyweight of 34.7 (SD = 0.85) kg were randomly assigned to six experimental diets containing 193, 174, 154, 135, 117, and 97 g/kg of crude protein (CP). Pigs were penned individually. There were five pigs in each diet. The faecal nitrogen output (NFO) showed a decreasing quadratic relationship with protein level. A linear relationship between protein level and urinary nitrogen excretion was observed (P =0.0001). The total nitrogen excreted showed a significant quadratic relationship to decreasing levels of CP in the diets (P =0.0001). The apparent digestibility of nitrogen had a linear relationship with dietary CP level (P =0.0005). A quadratic relationship between dietary protein level and N utilization was served (P =0.0001). The optimum protein level for total nitrogen excreted, nitrogen utilization and biological value of feed protein were attained at 135 g/kg protein level. The efficiency of nitrogen utilization supports the low protein diet. The present results suggest reducing the dietary protein level for Windsnyer pigs to decrease amount of excreted N that is deposited into the ironment. Keywords: apparent nitrogen digestibility, ideal protein level, nitrogen retention, excreted nitrogen, nitrogen utilization