Background: Residual feed intake(RFI) is an inheritable measure of feed efficiency that is independent on level of production. However, physiological and metabolic mechanisms underlying divergent RFI are not fully elu...Background: Residual feed intake(RFI) is an inheritable measure of feed efficiency that is independent on level of production. However, physiological and metabolic mechanisms underlying divergent RFI are not fully elucidated.This study was conducted to investigate dietary nitrogen(N) partitioning and microbial protein synthesis in lactating dairy cows divergent in phenotypic RFI.Results: Thirty Holstein dairy cows(milk yield = 35.3 ± 4.71 kg/d;milk protein yield = 1.18 ± 0.13 kg/d;mean ± standard deviation) were selected for the experiment to derive RFI. After the RFI measurement period of 50 d, the 10 lowest RFI cows and 8 highest RFI cows were selected. The low RFI cows had lower dry matter intake(DMI, P < 0.05) than the high RFI cows, but they produced similar energy-corrected milk. The ratios of milk to DMI(1.41 vs. 1.24, P < 0.01) and energy-corrected milk to DMI(1.48 vs. 1.36, P < 0.01) were greater in low RFI cows than those in the high RFI cows. The low RFI cows had lower milk urea nitrogen than that in the high RFI cows(P = 0.05). Apparent digestibility of nutrients did not differ between two groups(P > 0.10). Compared with high RFI animals, the low RFI cows had a lower retention of N(5.72 vs. 51.4 g/d, P < 0.05) and a higher partition of feed N to milk N(29.7% vs. 26.5%, P < 0.05).Conclusions: The results suggest that differences in N partition, synthesis of microbial protein, and utilization of metabolizable protein could be part of the mechanisms associated with variance in the RFI.展开更多
[Objectives] This study was conducted to explore the effects of new fly maggot protein feed on the mRNA expression of genes related to the TOR signaling pathway in loaches(Misgurnus anguillicaudatus). [Methods] Two ki...[Objectives] This study was conducted to explore the effects of new fly maggot protein feed on the mRNA expression of genes related to the TOR signaling pathway in loaches(Misgurnus anguillicaudatus). [Methods] Two kinds of test feed with equal nitrogen and energy were prepared by replacing 60% of the fish meal in the control group with the new fly maggot protein feed, i.e., Diet1(control group) and Diet2(60% fish meal replacement group). The feeding experiment was carried out in an indoor circulating water system, and the breeding period was 60 d. [Results] For the livers, the mRNA levels of TOR and 4EBP1 in the Diet2 group were significantly higher than those in the Diet1 group(P<0.05), while the expression of 4 EBP2 was lower than in the Diet1 group(P<0.05);and as to the muscles, the mRNA levels of TOR and 4EBP1 in the Diet2 group were significantly lower than those in the Diet1 group(P<0.05), while there was no significant change in the mRNA level of 4EBP2 between the two groups. [Conclusions] The replacement of fish meal by fly maggot cultures affected the mRNA expression of TOR, 4EBP1 and 4EBP2 in loach livers and muscles.展开更多
The effect of fishmeal quality on growth,feed conversion ratio and protein digestibility was studied in a growth experiment with shrimp and red seabream.The shrimp and fish were fed three diets varing in the quality o...The effect of fishmeal quality on growth,feed conversion ratio and protein digestibility was studied in a growth experiment with shrimp and red seabream.The shrimp and fish were fed three diets varing in the quality of the fishmeal used in the respective feeds: low quality fish meal,good quality fish meal,and Peru fish meal.The experiment lasted for 2 months.The shrimp and fish fed the feed with good quality fish meal showed significantly better feed conversion ratio,weight gain rate,protein digestibility than the other groups.展开更多
基金supported by grants from the National Natural Science Foundation of China(No.31872380)the China Agricultural Research System(Beijing,China No.CARS-36)
文摘Background: Residual feed intake(RFI) is an inheritable measure of feed efficiency that is independent on level of production. However, physiological and metabolic mechanisms underlying divergent RFI are not fully elucidated.This study was conducted to investigate dietary nitrogen(N) partitioning and microbial protein synthesis in lactating dairy cows divergent in phenotypic RFI.Results: Thirty Holstein dairy cows(milk yield = 35.3 ± 4.71 kg/d;milk protein yield = 1.18 ± 0.13 kg/d;mean ± standard deviation) were selected for the experiment to derive RFI. After the RFI measurement period of 50 d, the 10 lowest RFI cows and 8 highest RFI cows were selected. The low RFI cows had lower dry matter intake(DMI, P < 0.05) than the high RFI cows, but they produced similar energy-corrected milk. The ratios of milk to DMI(1.41 vs. 1.24, P < 0.01) and energy-corrected milk to DMI(1.48 vs. 1.36, P < 0.01) were greater in low RFI cows than those in the high RFI cows. The low RFI cows had lower milk urea nitrogen than that in the high RFI cows(P = 0.05). Apparent digestibility of nutrients did not differ between two groups(P > 0.10). Compared with high RFI animals, the low RFI cows had a lower retention of N(5.72 vs. 51.4 g/d, P < 0.05) and a higher partition of feed N to milk N(29.7% vs. 26.5%, P < 0.05).Conclusions: The results suggest that differences in N partition, synthesis of microbial protein, and utilization of metabolizable protein could be part of the mechanisms associated with variance in the RFI.
基金Supported by General Project of Natural Science Research in Higher Education Institutions in Jiangsu Province(18KJD240001)Xuzhou Science and Technology Planning Project(KC19200)2018“Qinglan Project”of Jiangsu Higher Education Institutions。
文摘[Objectives] This study was conducted to explore the effects of new fly maggot protein feed on the mRNA expression of genes related to the TOR signaling pathway in loaches(Misgurnus anguillicaudatus). [Methods] Two kinds of test feed with equal nitrogen and energy were prepared by replacing 60% of the fish meal in the control group with the new fly maggot protein feed, i.e., Diet1(control group) and Diet2(60% fish meal replacement group). The feeding experiment was carried out in an indoor circulating water system, and the breeding period was 60 d. [Results] For the livers, the mRNA levels of TOR and 4EBP1 in the Diet2 group were significantly higher than those in the Diet1 group(P<0.05), while the expression of 4 EBP2 was lower than in the Diet1 group(P<0.05);and as to the muscles, the mRNA levels of TOR and 4EBP1 in the Diet2 group were significantly lower than those in the Diet1 group(P<0.05), while there was no significant change in the mRNA level of 4EBP2 between the two groups. [Conclusions] The replacement of fish meal by fly maggot cultures affected the mRNA expression of TOR, 4EBP1 and 4EBP2 in loach livers and muscles.
文摘The effect of fishmeal quality on growth,feed conversion ratio and protein digestibility was studied in a growth experiment with shrimp and red seabream.The shrimp and fish were fed three diets varing in the quality of the fishmeal used in the respective feeds: low quality fish meal,good quality fish meal,and Peru fish meal.The experiment lasted for 2 months.The shrimp and fish fed the feed with good quality fish meal showed significantly better feed conversion ratio,weight gain rate,protein digestibility than the other groups.
