Dietary supplementation of laminarin improves the reproductive performance of sows and the growth of suckling piglets

Background Maternal nutrition is essential in keeping a highly efficient production system in the pig industry.Laminarin has been shown to improve antioxidant capacity,reduce the inflammatory response,and favor the homeostasis of intestinal microbiota.However,the effect of dietary supplementation of laminarin on the reproductive performance of sows and the growth of suckling offspring remains unknown.Methods A total of 40 Landrace×Yorkshire multiparous sows on d 85 of gestation,similar in age,body weight(BW),parity and reproductive performance,were randomly divided into four dietary treatments with 10 sows per treatment,receiving a control diet(basal pregnancy or lactating diets)and a basal diet supplemented with 0.025%,0.05%and 0.10%laminarin,respectively.The experiment lasted from d 85 of gestation to d 21 of lactation.Results Laminarin supplementation linearly increased number born alive per litter(P=0.03),average daily feed intake(ADFI,P<0.01),and total milk yield of sows during the lactation of 1–21 d(P=0.02).Furthermore,maternal laminarin supplementation increased the average daily gain(ADG)of piglets while tending to reduce the culling and death rate before weaning.In addition,alterations to the composition of colostrum and milk,as well as to serum inflammatory cytokines and immunoglobulins of sows were observed.The fecal microbiota profile of sows supported the improvement of reproductive performance in sows and the growth performance in suckling offspring.Conclusions Dietary supplementation of laminarin during late pregnancy and lactation could significantly improve reproductive performance of sows and growth performance of piglets.

Study on Breeding Practices and Reproductive Performance of Black-Head Somali Sheep under Traditional Management System: The Case of Awbarre District, Eastern Ethiopia

The study was conducted in the Awbarre district of the Fafen zone of the Somali regional state of Ethiopia. The objective of the study was to assess the breeding practices and reproductive performance of Black-head Somali sheep under a traditional management system. Purposive and simple random sampling techniques were used to select targeted kebeles and households, respectively. A total of 120 households were selected from four kebeles, each of 30 households, based on the production system and sheep population. Semi-structured questionnaires, group discussions, key informants interviews and field observations were used to generate the required data. The primary purpose of keeping sheep was for income generation, followed by saving as a future asset. The majority (89.2%) of the respondents separated male and female animals during herding. The selection criteria for breeding rams were appearance, growth, pedigree, and color while for breeding ewes were appearance, adaptability, pedigree, color, and lamb growth. The overall weaning age of Black-head Somali sheep in the study area was 3.7 months for both males & females. The castration of male sheep was common for the purpose of fattening, fattening with breeding control and breeding control as well. The castration is mainly performed during the summer and autumn and the methods of castration were both traditional and modern methods, the traditional castration method being the most important one in pastoral areas. The age of sexual maturity was 7.64 months for rams and 8.97 months for ewe’s male and female lambs in the pastoral area and 8.42 & 8.38 for rams & ewes in agro-pastoral and overall lambing interval was 11 months. On average, the ewe of Black-head Somali sheep in pastoral & agro-pastoral could produce 9.49 & 9.57 lambs, respectively in their lifetime. As the pastoralists and agro-pastoralists indicated the source of the breeding ram was their own, so the exchange of breeding ram is recommended to minimize the risk of inbreeding and further studies of on-farm performance investigation would be necessary to be carried out so as to understand the uniqueness of the breed better.

Effects of melatonin implantation on cashmere yield,fibre characteristics,duration of cashmere growth as well as growth and reproductive performance of Inner Mongolian cashmere goats

Background： Exogenous melatonin could induce cashmere growth. However, induced growth of cashmere fleece by melatonin implants cannot be combined with the typical growth, resulting in earlier shedding followed by another cycle of cashmere growth. To address this issue, we examine the effects on the cashmere yield, fibre characteristics, and the growth and reproductive performance of cashmere goats of planned administration of melatonin. Methods： Eighteen half-sib, female goats were assigned to two treatments （n = 9） including a control and a treatment where melatonin （2 mg/kg BW） was implanted at the end of April and end of June. Cashmere growth and shedding were observed for approximately ] year following implantation. Fibre samples were collected monthly to determine cumulative cashmere length. Initiation and cessation dates for cashmere growth as well as the rate of cashmere growth were calculated. Cashmere yield, weight gain of dam, kidding date, litter size, and birth weight were also recorded. Results： Melatonin implantation increased cashmere yield by 34.5 % （control 553.7 g vs. melatonin 745.0 g; P〈 0.01）, cashmere length by 21.3 % （control 95.2 mm vs. melatonin 115.4 mm; P 〈 0.01）, and decreased fibre diameter by 4.4 % （control 14.6 pm vs. melatonin 14.0 IJm; P 〈 0.03）. In melatonin-treated goats, the average initiation date was earlier than in control goats （May 18, 2013 vs. July 2, 20]3; P〈 0.01） but there was a similar cessation date （March 22, 2014 vs. March 27, 2014）. Consequently, the duration of cashmere growth was longer in melatonin-treated goats than in control goats （307 vs.270 days; P 〈 0.01）. The final BW, average daily gain, kidding date, litter size, and birth weight were not influenced by melatonin implantation. Conclusions： These data indicate that melatonin implantation （2 mg/kg BW） on two occasions （late April and June） increased cashmere yield by combining the induced growth of cashmere fleece with the typical growth and decreased the fibre diameter without changing dam growth rate or reproductive performance.

Inclusion of purified dietary fiber during gestation improved the reproductive performance of sows

Background: This study aimed to investigate the impacts of guar gum and cellulose as the source of dietary fiber during gestation on the reproductive performance of sows.Methods: A total of 210 sows(parities 3–6) were randomly allocated into six diets(n = 35) throughout gestation to feed graded levels of dietary fiber(DF), including a corn-soybean meal-based control diet with no wheat bran inclusion(CON, 12.5% DF), a wheat bran-rich diet(DF1, 17.4% DF), and another 4 diets(DF2, 17.7% DF;DF3, 18.1%DF;DF4, 18.4% DF;DF5, 18.8% DF) in which wheat bran were equally substituted by 1%, 2%, 3% and 4% purified FIBER MIX(guar gum and cellulose, 1:4). All sows received similar DE and other nutrients throughout gestation.Results: DF treatment during gestation resulted in normal fecal score(1 to 5 with 1 = dry and 5 = watery) in sows compared with those received the CON diet(P < 0.05). The number of total born piglets had a tendency to be affected by dietary treatment(P = 0.07), and correlation analysis revealed a linear response of total born to dietary fiber levels during gestation(P < 0.01). Sows received the DF2, DF3, and DF5 diets during gestation had a greater ADFI during lactation compared with those in the CON group(P < 0.05) without affecting the daily body weight gain of suckling piglets. Gut microbiota compositions were dramatically changed by the gestation stage and some of those were changed by DF inclusion. Fecal acetate, propionate, and butyrate of sows were markedly increased in late gestation, and butyrate contents in feces of gestating sows were significantly affected by DF levels(P < 0.01).Serum concentrations of pro-inflammatory TNF-α were decreased and anti-inflammatory IL-10 was increased on day30 of gestation by DF levels(P < 0.05).Conclusions: In summary, increasing dietary fiber levels by guar gum and cellulose during gestation improved the reproductive performance of sows, which might be related to changes in immunity and gut microbiota of sows.

A systematic review and meta-analysis of dietary fat effects on reproductive performance of sows and growth performance of piglets

Effects of added fat in sow diets on the sows’reproductive performance and offspring growth performance are influenced by multiple factors such as genetics,nutrition,parity,ambient temperatures,and farm management.Individual studies cannot cover all these factors.With the view to address this challenge,we searched all studies that were published from 1986 to 2020,and performed a systematic review and meta-analysis on the fat effect.In total,19 papers were collected and analyzed.Fat supplementation in sow diets during late gestation and lactation decreased average daily feed intake(ADFI,P<0.05)and tended to increase average daily energy intake(ADEI,P=0.11).It had no impact on litter weights at birth(P=0.40)or weaning(P=0.46).It increased total numbers of piglets at birth(P=0.07),but had no effect on liveborn per litter(P=0.90)or survival rate(P=0.48)of piglets to weaning.Fat supplementation had no significant effect on sow body weight loss(P=0.67)or backfat thickness changes(P=0.66),but sows fed diets with added fat had increased milk fat concentration(P=0.03)and shorter wean to estrus intervals(WEI,P=0.01).In specific circumstances,fat supplementation tended to improve growth performance of piglets with low litter weights at birth(P=0.14),or when the sows lost large amounts of body weight during lactation(P=0.11).The level of supplemented fat was 10%and higher would decrease liveborn per litter at neutral temperature(P=0.10).The meta-analysis revealed that fat supplementation to sows diet during late gestation and lactation can be beneficial for sow reproductive performance and litter growth performance.

Effects of Different Dietary Crude Protein Levels on Reproductive Performance in Breeder Roosters

[Objective] To investigate effects of different dietary crude protein levels on reproductive performance and find out the optimal additive proportion of crude protein. [Method] A total of 45 New Yangzhou breeder roosters at 21 weeks old were sampled and divided into three groups, namely, low-protein diet group, medium-protein diet group and high-protein diet group. They were fed with diets respectively at crude protein levels of 17.23%, 13.04% and 11.32%. The sperm volume, testicular traits and levels of reproductive hormones were analyzed during the whole repro- ductive period. [Result] The sperm volume, sperm motility and sperm density of the medium-protein diet group were higher than that of the other two groups, and the sperm deformity rate of the medium-protein diet group was lowest. The rooster＇s testicular traits including weight, volume and testis indexes were not significantly affected by different protein levels, but the testis shrank slowly with aging （ P 〈 0.05）. The levels of testosterone （T）, luteinizing hormone （LH） and follicule stimulating hormone （FSH） in plasma were respectively 6.34%, 19.64% and 3.88% higher in the lowprotein diet group than in the medium-protein diet group, and these indexes were respectively 7.20%, 17.54% and 9.84% higher in the low-protein diet group than in the high-protein diet group. But all these differences were not significant. [ Conclusion] The breeder roosters fed with the diet at the crude protein level of 13.04% show better reproductive performance and economic efficiency.

A novel method to improve sow reproductive performance:Combination of pre-weaning immunization against inhibin and post-insemination hCG treatment

The feasibility of a novel method to improve sow reproductive performance by combining inhibin immunization and hCG treatment was tested using in vivo and in vitro experiments. In the in vivo experiment, 106 sows were administered an inhibin immunogen on day 7 prior to weaning, and 56 non-treated sows served as the controls. Sows exhibiting oestrous behaviour on day 5 after weaning were artificially inseminated. On day 5 post-insemination, a subset of 50 inhibin-immunized sows received an injection of 1000 IU human chorionic gonadotropin (hCG). Our results showed that pre-weaning immunization against inhibin marginally improved (P=0.068) total litter size and significantly increased (P=0.044) the live litter size. The overall differences in farrowing rates and live litter size tended toward significance (P=0.10) in the three groups, and the differences in total litter size were not significant (P=0.18). In the in vitro experiment, activin and hCG dose-dependently suppressed (P<0.001) and stimulated (P<0.001) progesterone (P4) secretion in cultured pig granulosa cells (GCs), respectively, and the suppression effect of activin was reversed (P<0.001) by hCG. Activin suppressed P4 secretion mainly by downregulating (P<0.001) the expression of StAR, Cyp11a1, and 3β-HSDII, whereas hCG prevented (P<0.001) the suppression effects. These results indicate that the combination of pre-weaning immunization against inhibin and postinsemination hCG treatment provides a novel method for improving sow reproductive performance.

Genetic analysis of reproductive performance in sows during porcine reproductive and respiratory syndrome(PRRS)and porcine epidemic diarrhea(PED)outbreaks

Background: Porcine reproductive and respiratory syndrome(PRRS) is one of the most infectious swine diseases in the world, resulting in over 600 million dollars of economic loss in the USA alone. More recently, the USA swine industry has been having additional major economic losses due to the spread of porcine epidemic diarrhea(PED).However, information regarding the amount of genetic variation for response to diseases in reproductive sows is still very limited. The objectives of this study were to identify periods of infection with of PRRS virus(PRRSV) and/or PED virus(PEDV), and to estimate the impact their impact on the phenotypic and genetic reproductive performance of commercial sows.Results: Disease(PRRS or PED) was significant(P < 0.05) for all traits analyzed except for total piglets born.Heritability estimates for traits during Clean(without any disease), PRRS, and PED ranged from 0.01(number of mummies;Clean and PED) to 0.41(abortion;PED). Genetic correlations between traits within disease statuses ranged from-0.99(proportion born dead with number weaned;PRRS) to 0.99(number born dead with born alive;Clean). Within trait, between disease statuses, estimates ranged from-0.17(number weaned between PRRS and PED) to 0.99(abortion between Clean and PRRS).Conclusion: Results indicate that selection for improved performance during PRRS and PED in commercial sows is possible and would not negatively impact performance in Clean environments.

Determination of Physiological Biochemical Parameters and Reproductive Performance in Transgenic sFat-1 Gene Pigs

[Objective] The aim was to evaluate the health of transgenic sFat-1 gene pigs in order to provide a reference for the breeding selection of pig excellent individuals. [Method] 15 physiological biochemical parameters and reproductive performances of 21 negative control pigs and 20 transgenic sFat-1 gene pigs were determined. [Result] The liver functions of some transgenic sFat-1 gene pigs were hurted lightly,and the reproductive performance also decreased lightly. [Conclusion] The determination of physiological biochemical parameters and reproductive performance in transgenic pigs could be taken as one of effective methods in environmental safety evaluation of transgenic pigs.

Effects of Different Levels of Bee Pollen in Feed on Reproductive Performance of Xenocypris davidi Bleeker

Feeding growth test of Xenocypris davidi Bleeker was carried out in outdoor ponds for 8 weeks.Three experimental group feeds were made by adding bee pollen to the basic feed at the dosage of 1%,2%and 3%,with fish meal,soybean meal,cotton meal and vegetable meal as protein source,and soybean oil as fat source for basic feed.The results showed that the sexual maturation rates of the parent fish in the bee pollen group with the addition of 2%and 3%were signi ficantly higher than that in the control group and the bee pollen group with the addition of 1%(P<0.05).From the perspective of egg quality,egg diameter,fertilization rate,hatching rate and the length of membrane larvae in the control group were significantly lower than that in the bee pollen group(P<0.05).From the perspective of sperm quality,the addition of high proportion of bee pollen in the diet of parental fish can significantly improve the reproductive performance of male parental fish(P<0.05).Compared with the control group,the addition of 2%bee pollen increased sperm density by 45.3%,sperm motility by 12.7%and the rate of sperm malformation by 21.0%.All things considered,the best amount of yellowtail was 2%bee pollen.

Effect of Eliminated the Breeding Pigs with Unqualified CSFV Antibody on Sows' Reproductive Performance and Pigs' Growth Performance

[Objective] The aim was to explore the effect of eliminated the breeding pigs with unqualified CSFV antibody on sow's reproductive performance and pig's growth performance so as to provide a scientific basis for the eliminating of the breeding pigs with unqualified CSFV antibody in large-scale pig farms.[Method] Serum samples from three scale pig farms were collected and tested with HerdChek CSFV-ELISA kit,then provided a certain scientific basis for scale pig farm to eliminate the unqualified(antibody blocking rate<50%)breeders after booster immunization.[Result ] After eliminating the breeding pigs with unqualified CSFV antibody,the average litter number of piglet in three pig farms(A,B,C)were increased by 0.29(P<0.05),0.40(P<0.01),0.39(P<0.01)respectively;the average number of survival piglets were increased by 0.54(P<0.01),0.35(P<0.01),0.62(P<0.01)respectively;the average litter number of weaned piglets were increased by 0.65(P<0.01),0.71(P<0.01),0.81(P<0.01)respectively.The difference in weight gain of piglet at 30-60 d of age was extremely significant(P<0.01),but inconspicuousness for the swine pregnancy rate,the survival rate of weaned piglet and piglet at 30-60 d of age.[Conclusion] The eliminating the breeding pigs with unqualified CSFV antibody can significantly improve the performance of breeder and piglets.

Growth Development and Reproductive Performance of Congjiang Fragrance Pig

[Objective] The paper was to determine whether the germplasm resources of Congjiang fragrance pig had changed over the past 30 years. [Method]The growth development and reproductive performance of 100 pigs from six towns in central fragrance pig producing area and Congjiang fragrance pig stock seed farm were measured,and further compared with the data in Guizhou Livestock and Poultry Breeds 1986. [Result]The growth and development status was basically consistent,and the average litter size was at a downward trend: the first litter decreased by 26. 2%; the second litter decreased by 7. 0%; the third litter decreased by8. 55%. [Conclusion] The study laid the foundation for vigorous promotion of Congjiang fragrance pig in industrial development process,acceleration of breeding pace,gradual updating of farming breeds by farmers and improvement of production efficiency of fragrance pig.

Effects of Dietary Metabolizable Energy and Crude Protein Levels on Reproductive Performance of Magang Geese

[ Objective] To investigate the effects of different levels of metabolizable energy and crude protein on egg laying performance and hatch- ing efficiency in Magang geese. [Method] The healthy Magang geese at 2 years old were randomly assigned into four groups, group Ⅰ, group Ⅱ, group Ⅲ and control group. They were fed with diets at different levels of metabolizable energy and crude protein, and then their eggs were collect- ed and hatched. During the test, their health was observed, and the egg weight, egg yield and hatching rate were recorded. [ Result] The average egg laying rates and average egg weight were significantly higher in the group Ⅰ, group Ⅱ and group Ⅲ than in the control group. The hatchable egg rates and egg fertilization rates of the group Ⅰ, group Ⅱ and group Ⅲ were also increased, and significance was found between the group Ⅲ and the other group （P 〈 0.05）. The feed costs of the three test groups were lower than that of the control group, and the feed cost was higher in the group Ⅲ than that in the group Ⅰ and Ⅱ. [ Conclusion] The levels of metabolizable energy and crude protein in diet have significant effects on laying performance and hatching efficiency in Magang geese.

Research Progress on the Effects of Dietary Fiber Regulating Gut Microbiota on Sows Reproductive Performance

Dietary fiber(DF)is an essential nutrient in sow diet.It can increase sow satiety and prevent constipation.It can also regulate sow gut microbiota,and the interaction between the two can regulate sows reproductive performance and metabolic function and the growth performance of offspring piglets.It can be seen that the benefits of DF in sow production are inseparable from the interaction of gut microbiota.This paper reviewed the effects of DF on the diversity of sows gut microbiota,and the effects of DF-gut microbiota interaction on sows gut microbiota,metabolism,ovulation and lactation,as well as on offspring production performance,aiming to provide a new strategy for the application and research in sow diet.

Effect of Poly-β-hydroxybutyrate on Reproductive Performance and Larval Development of Fenneropenaeus chinensis

In the present study, Fenneropenaeus chinensis individuals were assigned into six groups, and fed with a diet supplemented with 0 （Control）, 0.5% （Group Eos）, 1.0% （Group E1.0）, 2.0% （Group E2.0）, 3.0% （Group E3.0） or 5.0% （Group E5.0） of poly-13-hydroxybutyrate （PHB） during their growth and spawning periods, to explore the effect of PHB on the reproductive performance of parents and the development of larvae. The experi- ment was lasted for 192 d to measure the mortality rate, relative percentage of survival（RPS）, weight gain rate（WGR）, specific growth rate （SGR） and cycle of gonadal development of parental shrimps, number of eggs, number of nauplii, stages of larval development and metamorphosis. The results indicated that PHB had an obvious effect on the fecundity of parental shrimps and growth performance of larva. Compared with control group, the mortality rate of broodstock in experimental groups decreased initially and increased subsequently with the increase of PHB concentration, while RPS showed an opposite pattern. The mortality rate of group E2.0 was the lowest among all groups, showing significant difference from that of other groups（P 〈 0.05） except group E1.0 （P 〉 0.05）. WGR of all experimental groups was higher than that of the control group, among which, group E2.0 and group E5.0 had significantly higher WGR than the control （P〈0.05）. However, there was no significant difference in the cycle of gonadal development between the experimental groups and the control group （P 〉 0.05）. The numbers of eggs and nauplii in the experimental groups were higher than those of the control group. And the numbers of eggs and nauplii in group E2.0 were significantly higher than those of the control （P 〈 0.05）, bud showed no significant difference from those of other groups （P 〉 0.05）. However, there was no significant difference in the duration of larval development and metamorphosis among all the groups. In summary, PHB is capable of improving the reproductive performance of parents and the survival and development of larva in F. chinensis, and 2.0% is the optimal concentration of PHB supplemented to the diet.

Study on Reproductive Performance of Improved Hybrid from Chinese Holstein Cattle

In order to overcome the problems such as decline in adaptability, low fertility and few utilization years due to continuously increasing coefficient of inbreeding of Chinese Holstein cattle, three dairy-beef dual-purpose cattle varieties （purebred Simmental, Montbeliard and Fleckvieh） were introduced as the male parents to be hybridized with Chinese Holstein cattle, so as to study the improvement effect in the reproduction performance and milk production performance of the hybrid cattle. The results showed that the first-filial generation of Montbeliard had a very significant difference in gestation period from Chinese Holstein cattle （ P 〈0.01）. The parity of Fleckvieh s first-filial generation had a very significant effect on 305 d milk yield （ P 〈0.01）; and for the first-filial generation of Montbeliard, mating times and open days significantly affected 305 d milk yield （ P 〈0.05）, and its total milk yield had a significant difference from Chinese Holstein cattle （ P 〈0.05）. Comprehensively, the reproduction traits of Montbeliard s first-filial generation are better than other two varieties.

Morphometric Characteristics and Reproductive Performance of Pasundan Cattle in the North Prianganese and Southern South Coast Region

This study aims to determine the morphometric characteristics and reproductive performance of Pasundan cows which are extensively reared on smallholder farms in the coastal areas of the south(Garut,Cianjur,and Sukabumi)and North Priangan(Bogor,Purwakarta,and Sumedang).This research is descriptive research with a qualitative approach.Production characterization was carried out using a simple method,namely by measuring the body surface including shoulder height,chest circumference,body length,and bodyweight of Pasundan cattle.Meanwhile,the reproductive characteristics discuss puberty,service per conception(S/C),conception rate(CR),calving rate,postpartum estrus,postpartum mating,days open(DO),calving interval(CI),calving birth weight,calving rate,and calves weight growth.Data were collected by survey,and the location was determined by purposive sampling in the area of the seed source with the largest population and the random sampling of livestock was determined purposively as many as 30 Pasundan cows from each region.Data were analyzed using quantitative descriptive analysis.The results showed that the morphometric characteristics of Pasundan cattle included mean shoulder height of 123.00±3.06a cm VS 121.34±2.82a in males and 110.34±2.78 vs 108.00±2.14a in females.Body length 115.74±3.30 cm VS 115.34±2.97acm in males and 112.67±2.97cm VS 109.67±1.82 cm in females.Chest circumference 145.67±2.97cm VS 142.67±2.67cm bulls and 136.00±2.95cm VS 131.00±2.92cm in females,Bodyweight 268.0±17.00 kg VS 246.00±7.00a for males and 215.0±15.00 kg VS 194.00±54.00kg in females.As for reproductive characteristics,it shows puberty of 20-24 months.,S/C 1.4-1.6,Conception rate 65-70%,calving rate 62.5-65%,Postpartum Estrus 50-60 days,postpartum mating 72-104 days,day-open 94-126 days and a calving interval of 12-14 months.Calves'birth weight was 18.0-18.5 kg and daily body weight gain ranged from 0.48 to 0.50 kg.It was concluded that the morphometric characteristics and reproductive performance of Pasundan cattle in the Pesisir Selatan area were better than North Priangan.

Effect of Divergent Selection for Plasma very Low Denstity Lipoprotein Concentration on Reproductive Performance in Broiler Chickens

The reproductive performance and abdominal fat of the high VLDL (H-VLDL) and low VLDL (L-VLDL) lines were studied after divergent selection for plasma very low density lipoprotein (VLDL) concentration in broiler chickens at 8 weeks of age. It was shown that the main reproductive traits were higher in L-VLDL line than H-VLDL line. The beneficial correlated responses of the reproductive traits were produced by the selection for plasma VLDL. 1) Plasma VLDL concentration was significantly correlated with abdominal fat (r=0.50, P<0.01), ahich was higher than that with plasma triglyceride concentration. There was a significant difference in abdominal fat between both lines but age increase or food restriction may decrease this difference. The H-VLDL line had about twice as much abdominal fat as had L-VLDL at 8 weeks of age, while its mean body weight was similar to that of the L-VLDL line from birtl to the end of laying. 2) Mortality from apparently stress-related causes by food restriction for H-VLDL line females began to increase from 15 weeks of age and was 21% (38/180) higher compared with 13% (23/180) for L-VLDL line females. 3) Age of 5% Lying for L-VLDL line was 3 days less than that of H-VLDL line, age of 50% Lying was 37 days less for L-VLDL line than H-VLDL line, and the age of laying peak was similiar in both lines. Rate of lay at peak in L-VLDL and H-VLDL lines were 70.3%, 66.4%, respectively. 4) Fertility rate in L-VLDL line was significantly higher than that of H-VLDL line at 27 weeks of age (P=0.01) and there was a little difference in fertility rates between H-VLDL and L-VLDL line during late laying period. There were no significant differences between H-VLDL and L-VLDL lines in of day-old healthy the numbers chicks and hatchabilities of fertile and total eggs wheres mean numbers of healthy day-old chicks per hen were more is L-VLDL line than in H-VLDL line. 5) Under food restriction, egg production was higher in L-VLDL line than in H-VLDL line. It should be emphasized that the rate and amount of egg production in L-VLDL line were both significant higher than in H-VLDL line during early laying period (from 23 to 43 weeks of age, P<0.01). The mean egg production of LF line hens was ll eggs more than that of HF line ones throughtout the laying period (from 23 to 62 weeks of age). 6) Eggs in L-VLDL line were slightly heavier than those in H-VLDL line. Feed conversion (FC) ratio for L-VLDL line was lower than that in H-VLDL line betwen 23 and 62 weeks of age (5.01 and 5.46, respectively), especially FC ratio of L-VLDL line was significantly lower than that of HF line during 23 and 43 weeks of age (P<0.01). Also FC efficiency of breeding hens was higher in L-VLDL line than in H-VLDL line.

Path analysis of desirable traits and evaluation of reproductive performance of Crassostrea sikamea in different ages

Kumamoto oysters(Crassostrea sikamea)are important marine aquaculture shellfish because of their taste and round shell shape.Due to its small size,selective breeding is required to improve its market size,but there are no reports on traits suitable for direction selection and reproductive productivity of Kumamoto oysters of different ages.In this study,path analysis and one-way ANOVA were used to explore the influential indices of oyster body weight and fecundity.The results showed that shell height was the main factor affecting the body weight of Kumamoto oysters at one-year-old and two-year-old,followed by shell length.Body weight was the main factor influencing fecundity,and shell height showed a significant correlation with fecundity.Therefore,shell height should be considered the first parameter for selection when selecting Kumamoto oysters for body weight as the direct selection target.When one-year-old and two-year-old Kumamoto oysters were selected as parents from Xiangshan Bay,hatching parameters and growth parameters of F1 generation larvae were measured.The fecundity and egg diameters were 1.72×10^(6)and 46.60±3.62μm,respectively,which were significantly greater than one-aged oysters(5.86×10^(5),40.26±3.52μm).The hatching parameters(fertilized egg size,fertilization rate,and hatching rate)and larval growth performance(D-stage veliger and veliger)were similar and did not differ significantly(P>0.05),and after metamorphosis,there was also no significant difference in shell height size at 40 days of age(P>0.05).Therefore,there was no significant effect of age on reproduction,larval development,and the early growth of Kumamoto oysters.These results could provide a basis for parental sources and proper traits for Kumamoto oyster selection,which is beneficial to developing and utilizing this excellent germplasm resource.

Optimizing feeding regimen of replacement gilts to improve their reproductive performance and retention rate of their first 2 parities

The effects of age,body weight(BW),and backfat thickness(BF)of replacement gilts at first estrus and first mating on their subsequent reproductive performance and retention of their first 2 parities as sows was evaluated.A total of 3,025 Danish replacement gilts were categorized by farm(allocated to 4 farms),cross combination,age,BW and BF at first estrus and first mating,estrous cycle number at first mating,and flush feeding before first mating.The result shows that all the factors mentioned above were significantly associated with reproductive performance and retention rates of the first 2 parities.Farm 3 had more piglets born alive per litter(BA)(P<0.05).Farms 3 and 4 had more healthy piglets per litter(HP)(P<0.05).Farm 4 had the most piglets weaned per litter(PW)(P<0.05).Landrace×Landrace×Yorkshire(L×L×Y)replacement gilts had the most total piglets born per litter(TB),BA,HP,PW and a higher retention rate of the 2 parities than Landrace×Yorkshire(L×Y)replacement gilts(P<0.05).In addition,flush feeding before first mating had the most TB,BA,HP,PW,and a higher retention rate of the 2 parities than no flush feeding(P<0.05).Because the effects of replacement gilts rearing parameters on reproductive performance traits differed,we used 100 replacement gilts as a unit and the total number of weaned piglets from the first 2 parities as a new index.Replacement gilts undergoing their first estrus between 180 and 210 d of age at 115 to 124.9 kg BW and 14 to 15 mm BF had significantly higher reproductive indexes for their first 2 parities per 100 replacement gilts.Replacement gilts that mated between 210 and 230 d of age at 140 to 149.9 kg BW and 15 to 16 mm BF had optimal reproductive indexes.These results provide a new insight into the complex relationships among these reproductive performance traits and may help guide successful management of replacement gilts as a pivotal starting point for future fertility and longevity of rearing herds.