Influence of Montmorillonite Nanocomposite on Tissue Levels of Lead and Blood Biochemical Parameters in Pigs Exposed to Lead

Eighteen (Duroc × Landrace × Yorkshire) castrated boars,55 days of age and weighing approximately 19 kg,were used to investigate the effects of montmorillonite nanocomposite on tissue levels of lead as well as changes in blood biochemical parameters in pigs fed lead contaminated diets.The barrows were randomly assigned to one of three treatments (n=6) including a control which were fed a basal diet based on corn and soybean meal.The remaining two groups were fed the basal diet supplemented with 10 mg/kg lead either with or without 0.5% montmorillonite nanocomposite for 50 days.Pigs treated with lead had significantly increased levels of lead in their tissues.Lead accumulated in all tissues of the body with the highest accumulation found in the hair.When montmorillonite nanocomposite was given along with lead,tissue concentrations of lead did not differ from the control.Fecal excretion of lead increased significantly in lead-exposed pigs treated with montmorillonite nanocomposite.A progressive and appreciable accumulation of lead was seen in blood with a concomitant increase in zinc protoporphyrin levels during the course of treatment.However,zinc protoporphyrin levels did not differ from the control when montmorillonite nanocomposite was administered along with lead.The activity of δ-amino levulinic acid dehydratase in blood was significantly increased in lead treated pigs compared with the control.However,in pigs treated with lead and montmorillonite nanocomposite in combination,the activity of δ-amino levulinic acid dehydratase was similar to control pigs.Our results indicate that montmorillonite nanocomposite treatment of pigs exposed to lead resulted in reduced lead concentrations in body tissues.It appears that montmorillonite nanocomposite functions by increasing fecal excretion of lead.     

Influence of Montmorillonite Nanocomposite on Tissue Levels of Lead and Blood Biochemical Parameters in Pigs Exposed to Lead

Eighteen (Duroc × Landrace × Yorkshire) castrated boars, 55 days of age and weighing approximately 19 kg, were used to investigate the effects of montmorillonite nanocomposite on tissue levels of lead as well as changes in blood biochemical parameters in pigs fed lead contaminated diets. The barrows were randomly assigned to one of three treatments (n = 6) including a control which were fed a basal diet based on corn and soybean meal. The remaining two groups were fed the basal diet supplemented with 10 mg/kg lead either with or without 0.5% montmorillonite nanocomposite for 50 days. Pigs treated with lead had significantly increased levels of lead in their tissues. Lead accumulated in all tissues of the body with the highest accumulation found in the hair. When montmorillonite nanocomposite was given along with lead, tissue concentrations of lead did not differ from the control. Fecal excretion of lead increased significantly in lead-exposed pigs treated with montmorillonite nanocomposite. A progressive and appreciable accumulation of lead was seen in blood with a concomitant increase in zinc protoporphyrin levels during the course of treatment. However, zinc protoporphyrin levels did not differ from the control when montmorillonite nanocomposite was administered along with lead. The activity of δ-amino levulinic acid dehydratase in blood was significantly increased in lead treated pigs compared with the control. However, in pigs treated with lead and montmorillonite nanocomposite in combination, the activity of δ-amino levulinic acid dehydratase was similar to control pigs. Our results indicate that montmorillonite nanocomposite treatment of pigs exposed to lead resulted in reduced lead concentrations in body tissues. It appears that montmorillonite nanocomposite functions by increasing fecal excretion of lead.      

Mechanisms Involved in the Growth Promotion of Weaned Piglets by High-level Zinc Oxide1

Dietary supplementation with high lev- els of zinc oxide （ZnO） is an effective method to prevent diarrhea and promote growth in weaned pig- lets. However, the mechanisms behind these beneficial effects are not well understood. Recent advances in this field indicated that the effects of ZnO on piglet growth are achieved through multiple regulatory path- ways rather than a single pathway. This review focu- ses on recent advances in the effects of high level ZnO on： 1 ） Zn status in weaned piglets; 2 ） intestinal microbe flora regulation; 3 ） intestinal structure and function;4） ion secretion in the intestine epithelium;5） intestinal immunology; and 6） secretion of brain-in- testine peptides. ZnO appears to regulate the intestinal microflora and decreases the release of histamine to prevent diarrhea. ZnO also increases the expression of intestinal insulin-like growth factor-1 （ IGF-1 ） and the IGF-1 receptor to ameliorate intestinal injury associat- ed with weaning, and mediates secretion of brain-gut peptides to stimulate food intake, to promote the growth of piglets. Better understanding of the underly-1 ing mechanisms should inspire us to supplement the diet for weaned piglets with ZnO and investigate new approaches to prevent diarrhea and enhance growth.     

Lead poisoning in feeder calves

A group of 90 feeder calves was accidentally exposed to lead for approximately 30 days. The source of the intoxication was determined to be contamination of feed ingredients from a railroad car. Fourteen calves died and 8 more were clinically affected. Blood samples were obtained from 24 exposed calves (16 clinically normal and 8 intoxicated), and the samples were analyzed for lead, delta-amino levulinic acid dehydrase activity, and free erythrocyte porphyrin. Blood lead values ranged from 0.44 to 1.16 parts per million. Amino levulinic acid dehydrase activity was not affected enough to be of diagnostic value, whereas free erythrocyte porphyrin was increased dramatically and consistently in lead-exposed cattle.     

Fortification of pork loins with docosahexaenoic acid(DHA) and its effect on flavour

Pork is traditionally low in docosahexanoic acid(DHA, C22:6n-3) and deficient in omega-3 fats for a balanced human diet. DHA as triglycerides was commercially prepared from the microalgae Schizochytrium and injected into fresh pork loins. Treatments of a mixed brine control(CON), 3.1% sunflower oil in mixed brine(SF) and a 3.1% DHA oil in mixed brine(DHA) were injected into pork loins at 10 mL/100 g and grilled at 205°C. After cooking, the CON and SF pork loins contained 0.03 to 0.05 mg DHA/g of pork and the DHA injected loins contained approximately1.46 mg DHA/g. This also changed the fatty acid profile of omega-6: omega-3 from, 5 to 1 in the CON pork, to a ratio of 1.7 to 1 in DHA pork. The appearance, odor, oxidation rates and sensory taste, as judged by a trained panel,determined the DHA injected meat to be, ‘slightly desirable' and gave lower ‘off flavour' scores, relative to the CON and SF injected pork. Pork can be fortified with DHA oil to 146 mg/100 g serving, which would meet half the recommended daily omega 3 fatty acid requirements for adult humans and would be desirable in taste.     

Conjugated Linoleic Acid and Dietary Fats Differentially Affect Hepatic ACAT Activity and LDL-Cholesterol in Postweanling Pigs Fed Low-Fat Diets1

ABSTRACT：Two separate studies tested the hypoth- esis that plasma low-density lipoprotein cholesterol LDL-C ） can be decreased by conjugated linoleic acid （CLA） by depressing hepatic acyl-coenzyme A： cholesterol acyltransferase （ACAT） activity. In the first experiment, 3 groups of 6 early-weaned piglets were fed low-fat diets containing either 1.5% CLA, 1.5% corn oil or 1.5% beef tallow;fat provided 8% of the energy intake. In the second experiment, 4 groups of 6 early-weaned piglets were fed high-fat di- ets containing either 15% beef tallow, 12% beef tal- low plus 3% CLA, 15% corn oil, or 12% corn oil plus 3% CLA; fat provided 29% of energy intake. Cholesterol was balanced across diets in both experi-ments. In pigs fed the low-fat diets, all dietary fats in- creased LDL-C and triacylglycerols and decreased high-density lipoprotein cholesterol （ HDL-C ） and very low-density lipoprotein cholesterol （VLDL-C）. LDL-C was the same in pigs fed low-fat tallow or low-fat CLA diets. However, ACAT activity was near- ly 80% higher in pigs fed the low-fat tallow diet than in pigs fed the low-fat CLA diets. All high-fat diets increased LDL-C, HDL-C and triacylglycerols equally with no effect on VLDL-C. There were no unique fat- ty acid effects of the high-fat diets on ACAT activity. We conclude that supplemental fats had differential effects on hepatic ACAT activity and LDL-C, but on- ly in pigs fed low-fat diets.     

Potential role of N-carbamoyl glutamate in biosynthesis of arginine and its significance in production of ruminant animals

Arginine （ARG） exerts many beneficial effects on animal body and enhanced angiogenesis, lactogenesis, which finally leads to the improvement in nitrogen （N） metabolism, reproduction, lactation, immunity and growth. Unfortunately, unprotected ARG will be degraded in the rumen and its price is high, thus feeding rumen-protected ARG seems to be uneconomical. Alternatively, N-carbamoyl glutamate （NCG） is structural analogue of N-acetyl glutamate, cofactor of cabamoyl phosphate synthetasel, is lower in rumen degradation compared to ARG. Additionally, rumen epithelial and duodenal cells have potentially utilized the NCG for ureagenesis. Supplementation of NCG to high yielding dairy cows increased plasma concentration of ARG and nitric oxide, decreased the plasma ammonia N and improved lactation performance and N utilization. Supplementation of NCG enhanced pregnancy rates in rats, improved litter size and fetal survival rate, thereby improved the reproductive performance of sows. Oral NCG supplementation increases plasma ARG and somatotropin levels, and increased growth rate and muscle protein synthesis in nursing piglets. The NCG is potential a relatively cheaper source of feed additive to offer vital compensation over oral administration of ARG, resulting in improved ruminant animal health and production. In this article, we reviewed the mechanism of AfiG biosynthesis by NCG and their significance in growth, reproduction, milk production and N utilization in ruminant animals.     

Deletions in the pyruvate pathway of Salmonella Typhimurium alter SPIl-mediated gene expression and infectivity

Background： Salmonella enter/ca serovar Typhimurium is a major foodborne pathogen worldwide. S. Typhimurium encodes type III secretion systems via Salmonella pathogenicity islands （SPI）, producing the major effector proteins of virulence. Previously, we identified two genes of Salmonella pyruvate metabolism that were up-regulated during chicken cell infection： pyruvate formate lyase I （pf/B） and b/functional acetaldehyde-CoA/alcohol dehydrogenase （adhE）. We were therefore interested in examining the role these genes may play in the transmission of Salmonella to humans. Methods： Mutant strains of Salmonella with single gene deletions for pflB and adhE were created. Invasion and growth in human HCT-8 intestinal epithelial cells and THP-1 macrophages was examined. Quantitative PCR was performed on 19 SPI-1 genes. Results： In HCT-8 cells, both mutant strains had significantly higher intracellular counts than the wild-type from 4 to 48 h post-infection. Various SPI-1 genes in the mutants were up-regulated over the wild-type as early as 1 h and lasting until 24 h post-infection. In THP-1 cells, no significant difference in internal Salmonella counts was observed; however, SPI-1 genes were largely down-regulated in the mutants during the time-course of infection. We also found five SPI-1 genes - hilA, hiIC hill）, sicP and rtsA - which were up-regulated in at least one of the mutant strains in log-phase broth cultures alone. We have therefore identified a set of SPI-1 virulence genes whose regulation is effected by the central metabolism of Salmonella.     

Comparison of acid-detergent lignin,alkaline-peroxide lignin,and acid-detergent insoluble ash as internal markers for predicting fecal output and digestibilily by caltie offered bermudagrass hays of varying nutrient composition

Background： The potential for acid-detergent insoluble ash （ADIA）, alkaline-peroxide lignin （APL）, and acid-detergent lignin （ADL） to predict fecal output （FO） and dry matter digestibility （DMD） by cattle offered bermudagrass [Cynodon doctylon （L） Pers.] hays of different qualities was evaluated. Eight ruminally cannulated cows （594 ± 35.5 kg） were allocated randomly to 4 hay diets： low （L）, medium low （ML）, medium high （MH）, and high （H） crude protein （CP） concentration （79, 111,131, and 164 g CP/kg on a DM basis, respectively）. Diets were offered in 3 periods with 2 diet replicates per period and were rotated across cows between periods. Cows were individually fed 20 g DM/kg of body weight in equal feedings at 08：00 and 16：00 h for a 10-d adaptation followed by a 5-d total fecal collection. Actual DM intake （DMI）, DMD, and FO were determined based on hay offered, ort, and feces excreted. These components were then analyzed for ADL, APL, and ADIA concentration to determine marker recovery and marker-based estimates of FO and DMD. Results： Forage DMI was affected by diet （P = 0.02）, and DMI from MH and H was greater （P 〈 0.05） than from L. Apparent DMD tended （P = 0.08） to differ among diets while FO （P = 0.20） was not affected by diet treatments. Average ADL recovery （1.16） was greater （P 〈 0.05） than that of ADIA （1.03） and APL （1.06）, but ADIA and APL did not differ （P = 0.42）. Estimates of FO and DMD derived using APL and ADIA were not different （P≥0.05） from total fecal collection while those using ADL differed （P 〈 0.05）. There was no diet by marker interaction （P≥ 0.22） for either FO or DMD. Conclusion： Acid-detergent insoluble ash and APL accurately predicted FO and DMD of cattle fed bermudagrass hay of varying nutrient composition. These internal markers may facilitate studies involving large numbers of animals and forages. Results from such studies may be used to develop improve     

Effects of Dietary Starch Source on via the Portal Vein Nutrient and Energy Absorption of Growing Pigs

Four crossbred （Duroc x Landrace x Yorkshire） boars, weighing an average of 22.40 ± 1.08 kg and fitted with permanent catheters in their portal and mesenteric veins as well as their carotid artery,were utilized in a 4 × 4 latin square design experiment in order to investigate the effects of different starch sources （maize ,brown rice, sticky rice, and resistant starch） on the absorption of energy sources through the portal vein. Portal blood flow averaged 30.68, 28.40, 29.99, and 30. 12 mL/min per kg BW for pigs fed the maize, brown rice, sticky rice, and resistant starch diets, respectively, and did not dif- fer （P 〉 0.05） between treatments. The absorptions of glucose, plasma ammonia, and total amino acids were significantly lower （P 〈 0.05 ） in pigs fed the resistant starch diet than pigs fed the other starch sources. In contrast, significantly （ P 〈 0.05 ） higher amounts of propionate and total volatile fatty acids were absorbed from the portal vein of pigs fed resistant starch than pigs fed diets based on maize, brown rice, or sticky rice. In addition, significantly （P 〈 0.05） more lactic acid was absorbed from the portal vein by pigs fed the sticky rice diet than pigs fed the other three diets. The energy absorbed from the portal vein in the form of glucose and amino-N as well as the total energy absorbed was significantly （P 〈 0.05） lower in pigs fed the resistant starch diet than pigs fed the other three starch sources. In contrast, the amount of energy absorbed in the form of volatile fatty acids was significantly （P 〈 0.05 ） higher in pigs fed resistance starch than pigs fed the other three starch sources. The total energy absorbed through the portal vein as a percentage of the gross energy and digestible energy consumed in pigs fed maize were 50.8% and 54.6%, respectively, which were significantly （P 〈 0.05 ） higher than the values in pigs fed resistant starch （41.5% and 46.6% respectively）. The results indicate that energy is absorbed in different forms and with different utilization efficiencies in the digestive tract of pigs as a result of feeding different starch sources. Starch sources supplying most of their energy in the form of glucose had higher energy utilization efficiencies, while starch sources supplying most of their energy in the form of volatile fatty acids or lactic acid had lower energy utilization efficiencies.     

Effects of Estradioi and Progesterone on the Numbers and Distribution of Mastocytes in the Uterus of Ovariectomized Rats

The purpose of this study was to investigate the effects of estradiol （E） and progesterone （P） on mastocyte distribution in the uterus of ovari- ectomized rats. Thirty-five adult female rats were divided randomly into seven groups：one sham operated control group （ SHAM ） ; one ovariectomized group （OVX） ;three ovariectomized plus E treatment grouPs （OVX ＋E 20,100,or 500 μg/kg body weight · d） ; and two ovariectomized plus P groups （ OVX ＋ P 2 or 10 mg/kg body weight · d）. Seven days after treatment, the contents of estradiol and progesterone in serum were detected by radioimmunoassay, and mastocytes in the uterus were stained by toluidine blue staining. Results were as following： （1） Compared to ovariectomized rat, the concent ration of estradiol in serum increased by 97. 13 % in OVX ＋ E 20 （P 〈 0.05）,204. 84 % in OVX＋E 100 （P〈0.05）,and 936.45 % in OVX ＋ E500 group （P〈0.05）;the progesterone concent ration increased by 77.25 % in OVX ＋P 2 （P 〈0.05） and 235.25 %in OVX ＋P 10 group （ P 〈 0.05 ）. （2） Compared to ovariectomized rat, the number of mast cells in uteri decreased by 32.65% in OVX ＋E 20,64.50 % in OVX ＋E 100 （P〈0.05）,74.49 % in OVX＋E500 （P〈0.05） and 70.67 % in OVX ＋P 10 groups （P〈0.05）. However, the number of mast cells increased by 66.73% in OVX ＋ P 2 group （ P 〈 0.05 ） compared with OVX. The trend of mast cells number in the rat uterus was decreased gradually with the increase of estrogen or progesterone concent ration. The number of mast cells in ovariectomized rat uterus was affected by estrogen or progesterone. These results demonstrated that estrogen or progesterone directly affected the number of mast cells in the uterus of rat.     

The effects of dietary fiber level on nutrient digestibility in growing pigs

The objective of this study was to investigate the effects of total dietary fiber level on nutrient digestibility and the relationship between apparent total tract digestibility of total dietary fiber, and soluble dietary fiber, insoluble dietary fiber and available energy. Sugar beet pulp was as the only fiber source. The experiment was designed as a 6 x 6 Latin square with an adaptation period of 7 d followed by a 5-d total collection of feces and urine. Feed intake tended to decrease （P =0.] O） as total dietary fiber level increased. The apparent total tract digestibility of dry matter, crude protein and gross energy decreased （P 〈0.0]） when total dietary fiber increased but the digestibility of soluble dietary fiber and insoluble dietary fiber increased （P 〈0.01）. The digestible energy and metabolizable energy content of diets decreased （P 〈0.01） as the total dietary fiber increased.     

Restricted nutrient intake does not alter serum-mediated measures of implant response in cell culture

Background: During nutritional stress, reduced intake may reduce the efficacy of anabolic implants. This study was conducted to evaluate basic cellular responses to a growth promotant implant at two intake levels.Methods: Sixteen crossbred steers(293 ± 19.3 kg) were used to evaluate the impact of anabolic implants in either an adequate or a restricted nutritional state. Steers were trained to individual Calan gates, and then randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement. Treatments consisted of: presence or absence of an anabolic growth implant(Revalor-XS, 200 mg TBA and 40 mg estradiol; IMPLANT or CONTROL) and a moderate energy, pelleted, starting cattle diet fed at either 2.0 × or 1.0 × maintenance energy(NEM) requirements(HIGH or LOW). Serum(d 0, 14, and 28) was used for application to bovine muscle satellite cells. After treatment with the serum(20% of total media) from the trial cattle, the satellite cells were incubated for 72 h. Protein abundance of myosin heavy chain(MHC), phosphorylated extracellular signal-related kinase(phospho-ERK), and phosphorylated mammalian target of rapamycin(phospho-mTOR) were analyzed to determine the effects of implant, intake, and their interaction(applied via the serum).Results: Intake had no effect on MHC(P = 0.85) but IMPLANT increased(P 0.01) MHC abundance vs. CONTROL.Implant status, intake status, and the interaction had no effect on the abundance of phospho-ERK(P ≥ 0.23).Implanting increased phospho-mTOR(P 0.01) but there was no effect(P ≥ 0.51) of intake or intake × implant.Conclusions: The nearly complete lack of interaction between implant and nutritional status indicates that the signaling molecules measured herein respond to implants and nutritional status independently. Furthermore, results suggest that the muscle hypertrophic effects of anabolic implants may not be mediated by circulating IGF-1.     

Subcutaneous fatty acid composition of steers finished as weanlings or yearlings with and without growth promotants

Background: The current study evaluated the subcutaneous fatty acid(FA) composition of calf- and yearling-fed stee with or without growth promoting implants. Crossbred steers(n = 112; 267 ± 5.0 kg) of the same contemporary group were allocated to one of four production system and implant strategy based treatments in a completely randomized design with a 2 × 2 factorial arrangement of treatments.Results: There were no interactions(P 0.05) between production systems and growth promoting implants for the total and individual subcutaneous FA. Yearling as opposed to calf finishing reduced(P 0.05) subcutaneous proportions of C20:3n-6, trans(t)12-18:1, C14:0, several minor cis-monounsaturated FA(c-MUFA; c9-14:1, c11-16:1,c11-18:1, c12-18:1, c13-18:1, c9-20:1 and c11-20:1), and increased(P 0.05) subcutaneous proportions of t11c15-18:2,total and individual branched-chain FA. Subcutaneous fat from steers implanted with growth promotants had higher(P 0.05) proportions of total polyunsaturated FA(PUFA), total n-6 PUFA, C18:2n-6 and individual t-18:1isomers(t6 to t10) compared to non-implanted steers.Conclusions: Overall, current findings show that production systems and growth promotants led to only minor differences in subcutaneous FA composition of beef steers.     

Effects of Rumen-protected Methionine on Rumen Fermentation,lactation Performance and Plasma Characteristics in Dairy Cows

The objective was to evaluate effects of rumen-protected methionine （RP-Met） supplementation on rumen fermentation, lactation performance and plasma characteristics in dairy cows. Twenty-four multiparous （2.2 - 0.40 parity） Holstein dairy cows, averaged 620 ± 12.3 kg of BW, 68 ± 2.5 day in milk and daily milk production averaged 26.0 ±0.3 kg/cow were used in a replicated 4 × 4 Latin square experiment. The treatments were： control （without RP-Met）, LRP-Met, MRP-Met and HRP-Met with 20, 40 and 60 g RP-Met per cow per day, respectively. RP-Met was hand-mixed into the top one-third of the daily ration. Experimental periods were 30 days with 15 d of adaptation and 15 d of sampling. Dry matter （DM） intake and milk yields were not affected （P 〉 0.05） with increasing RP-Met supplementation. Yields of 4%FCM, ECM, milk fat and milk protein were higher （P 〈 0.03） for RP-Met supplementation than control and were quadratically （P 〈 0.05） changed due to the higher percentage of milk fat and protein for RP-Met supplementation than control （P 〈 0.03）. Ruminal pH tended to be lower （P = 0.071） for RP-Met supplementation than control, whereas total VFA concentration tended to be higher （P = 0.086） for RP-Met supplementation than control. Ratio of acetate to propionate decreased linearly （P = 0.001） from 4.01 to 3.57 as RP-Met supplementation increased due to the increase in propionate production. Digestibilities of DM, OM, CP, NDF and ADF in the total tract were higher （P 〈 0.05） for RP-Met supplementation than control and were quadratically （P 〈 0.05） increased with increasing RP-Met supplementation. Plasma concentrations of glucose not affected （P 〉 0.05） with RP-Met supplementation, Plasma concentrations of non-esterified fatty acids （NEFA） were significantly lower （P = 0.017） for RP-Met supplementation than control and were linearly （P = 0.011） changed. Plasma concentrations of beta-hydroxybutyrate tended to be lower （P = 0.068） for RP-Met supplementation than control and were linearly （P = 0.001） changed. The present results indicate that supplementation of diet with RP-Met improved the content of milk fat and protein, rumen fermentation and feed digestion, decreased plasma concentrations of NEFA. It was suggested that the RP-Met stimulated the digestive microorganisms or enzymes in a dose-dependent manner. In the experimental conditions of this trial, the optimum RP-Met dose was about 25 g RP-Met per cow per day.     

Mammary gland growth and vascularity at parturition and during lactation in primiparous ewes fed differing levels of selenium and nutritional plane during gestation

Background： Objectives were to examine the effects of selenium （Se） supply and maternal nutritional plane during gestation on mammary gland growth, cellular proliferation, and vascularity at parturition and d 20 of lactation. Rambouillet primiparous ewes （n = 84） were allocated to treatments in a 2 x 3 factorial. Factors were dietary Se （adequate Se [ASe, 11.5 μg/kg BW] or high Se [HSe, 77.0 μg/kg BVV]） and nutritional plane （60% IRES], 100% [CON], or 140% [EXC]）. At parturition, lambs were removed and 42 ewes （7/treatment） were necropsied. Remaining ewes were fed a common diet meeting requirements for lactation and mechanically milked twice daily until necropsy on d 20. At both necropsy periods, mammary glands were dissected and tissues harvested. Samples were analyzed for RNA, DNA, and protein content, cell proliferation, and vascularity. Where interactions were present （P 〈 0.05）, least squares means from the highest-order interaction are presented. Results： Final body weight of ewes was least （P 〈 0.002） in RES, intermediate for CON, and greatest for EXC, regardless of stage of the ewe at necropsy （parturition or d 20 of lactation）. In ewes necropsied at parturition, mammary glands were heavier （P = 0.02） in EXC compared to RES, with CON intermediate. Concentration of RNA （rag/g） was decreased （P= 0.01） in EXC compared to CON at parturition. There was a tendency （P= 0.07） for a Se by nutrition interaction in percentage of cells proliferating where ASe-EXC ewes had greater （P_〈 0.02） number of proliferating cells then all other treatments. Mammary vascular area tended （P = 0.08） to be affected by a Se by nutrition interaction where ASe-CON had less （P= 0.007） vascular area than HSe-CON ewes. In ewes necropsied at d 20 of lactation, the number of alveoli per area was decreased （P 〈- 0.05） in RES compared to CON and EXC-fed ewes. Conclusions： Results of this study indicate that proper maternal nutritional plane during gestation is important for mammary gland development, even out to d 20 of lactation.     

The Effect of Dietary Sulphate Copper Supplementation on Growth Performance,Intestinal Digestive Enzymes and Absorptive Transporters in Weanling Pigs1

The experiment was conducted to as- sess the effects of dietary supplementation of Cu on the growth performance, digestive enzymes, tissue minerals and absorptive transporters in small intestinal mucosa of weanling pigs. One hundred crossbred pigs weaned at 28 ＋ 2 d of age were assigned randomly to one of the following diets with 5 replicates：corn-soy- bean basal diet with 10,100,175,250 mg/kg of Cu as CuSO4·5H20. The results showed that 250 mg/kg Cu had a positive effect （ P 〈 0.05） on average daily gain, daily feed intake and ratio of gain/feed. Com- pared to 10 mg/kg Cu, higher Cu had significant effect on the apparent digestibility of protein and fat （P 〈 0.05 ）. The supplementing of Cu improved am- ylase and lipase activity in jejunum content and lipase in pancreas （ P 〈 0.05） and had no effect on intestinalmorphology. The liver Cu elevated approximately 4- fold in pigs fed diet with 250 mg/kg Cu compared with pigs fed diet with 10 mg/kg Cu, no increases were observed in pigs receiving the lower level of Cu （100 and 175 mg/kg）. Both Fe and Zn contents in kidney and liver were not affected by Cu supplemen- tation. There was no positive effect （ P 〉0.05） of Cu supplementation on PepT1 （peptide transporter 1 ） and SGLT1 （sodium/glucose cotransporter） mRNA abundance in intestinal mucosa. However, higher sup- plementing level （250 mg/kg） significantly elevated the DMT1 （divalent metal transporter） mRNA abun- dance in duodenum mucosa. These results suggested that dietary supplementation with 250 mg/kg Cu could improve growth performance, nutrient digestibil- ity and intestinal enzyme activities of weanling pigs.     

Review on the development of genotyping methods for assessing farm animal diversity

Advances in molecular biotechnology have introduced new generations of molecular markers for use in the genetic improvement of farm animals. Consequently, more accurate genetic information can be obtained to better understand existing animal genetic resources. This review gives a brief summary on the development of genetic markers including both the classical genetic markers and more advanced DNA-based molecular markers. This review will help us better understand the characteristics of different genetic markers and the genetic diversity of animal genetic resources.