An attempt was made to increase free amino acids (FAA) concentrations in eggs of red snapper Lutjanus campechanus as part of an induced spawning protocol. Mature female red snapper were given intramuscular injections of human chorionic gonadotropin (HCG) at a 1100IUkg(-1) of female body weight. Immediately after the HCG injection, one set of females received an intramuscular injection of FAA in a buffered saline solution at a dose of 20mg FAA cocktail kg(-1) of body weight. The FAA cocktail was 25% isoleucine, 25% leucine, 25% lysine and 25% valine on a molecular weight basis. A second set of fish did not receive the FAA supplement. Both sets of fish were equally successful in spawning with ovulation occurring 21-32.5h post injection. Injection of FAA into brooders as eggs began final maturation and hydration resulted in an increase in leucine (nmoles mg egg(-1)) and a slight increase in isoleucine (nmoles egg(-1)) in recently ovulated eggs. FAA supplementation via brood injection altered FAA utilization rates by embryos and during larval development, resulted in a greater yolk sac and oil globule reserve in larvae as they approached the time of first feeding.

Yorkshire pigs(n=32) were used to determinethe effect of supplementing grower-finisher diets with plum juiceconcentrate (PJC) on microbial shedding in pig feces. Pigs were sortedby weight and sex (n=16 barrows,n=16 gilts) and assigned to penswith 2 pigs per pen. Pens were randomly allotted to 1 of the 4 diets:0 (control), 0.5, 1.0, or 3.0% PJC. Fecal samples were collected fromone pig per pen on d 0, 1, 7, 14, 28, and 56 and the last day on feed(group 1=d 84; group2=d 98). The ham of each pig wasswabbed at slaughter. Fecal and ham swab samples were plated andenumerated for anaerobic and aerobic bacteria, Salmonella spp., andEscherichia coli. On d 28, the diet supplemented with 1.0% PJC reduced(P<0.05) anaerobic countcompared with the 0.5% PJC diet. Supplementing 1.0% PJC in the dietdecreased (P<0.05) anaerobiccount when comparing d 0 to the last day on feed. There was aquadratic trend between aerobic counts and days on feed, with thelowest (P<0.05) count on d14. Aerobic count was lower(P<0.05) on the last day offeeding than on d 0. Salmonella spp. were not present in any samplethroughout the experiment. In conclusion, supplementing PJC up to 3.0%had little effect on fecal microbial shedding in thisstudy.

Yorkshire pigs (n=32) were used to determine the influence of supplementation of plum juice concentrate (PJC) on growth and carcass and quality characteristics of pork. Pigs were sorted by weight and sex (n=16 barrows, n=16 gilts) and assigned to 16 pens with 2 pigs per pen. Pens were randomly allotted to 4 diets: 0 (control), 0.5, 1.0, or 3.0% PJC. During the feed trial, feed intake and weight gain were monitored every 14 d. Pigs were slaughtered at an average pen weight of 114kg (group 1=84 d; group 2=98 d). Supplementation of PJC did not affect (P>0.05) animal performance. Supplementation of PJC did not affect (P>0.05) carcass characteristics. However, gilts had a larger loin muscle area (P=0.02) and less fat at the 10th rib (P=0.01) than barrows. Supplementing PJC had little effect on pork quality. However, pork from barrows produced less drip loss (P=0.02) in comparison with gilts. In conclusion, supplementation of PJC up to 3.0% in the diet did not affect growing-finishing pig performance, carcass characteristics, or pork quality.

Live foods used in a marine fish hatchery must provide the nutrients needed for the rapidly developing larvae. Marine pelagic fish eggs can contain up to 50% of their total amino acid pool as free amino acids (FAA), of which most is used up shortly after the onset of exogenous feeding as a source of energy. Copepod nauplii are richer in FAA than many traditional foods given to marine fish larvae. However, copepod nauplii can be difficult to produce in mass quantities in the hatchery and are more readily available by capture from the wild. The process of capture and acclimation may impact the nutrient quality of such nauplii. This study describes the FAA profile of nauplii of Apocyclops panamensis collected from low salinity fertilized brackish-water ponds, the effects of acclimation from 6.6‰ to 30‰ seawater on the FAA profile, and the feasibility of direct enrichment of nauplii with isoleucine, leucine, lysine and valine. Nauplii were exposed to four treatment protocols over a 3h period and sampled for FAA profiles, 1) no salinity change, 2) direct transfer to 30‰, 3) acclimated to 30‰, and 4) acclimated+FAA enrichment. Nauplii collected from 6.6‰ salinity ponds had a mean total FAA content of 27.22±5.85nmol·mg−1 w.w. nauplii at the time of collection. Forty-two percent of the total was comprised of essential amino acids of which arginine, lysine, leucine and valine were the most prevalent, and 55% were non-essential amino acids, primarily glutamic acid, alanine, proline, asparagine and glycine. A direct transfer of nauplii from a salinity of 6.6‰ to 30‰ resulted in a significant reduction in total FAA (TFAA) particularly in essential FAA (EAA). Acclimation of nauplii from a salinity of 6.6‰ to 30‰ over 3h resulted in a significant increase in TFAA and particularly in non-essential FAA (NEAA). The addition of isoleucine, leucine, lysine and valine to the holding water during acclimation further increased their concentrations in the nauplii after a 3h exposure.

The free amino acids (FAA) profile was determined for newly fertilized eggs and resultant larvae from wild-caught red snapper Lutjanus campechanus induced to spawn with hCG. Yolk sac and oil globule volumes of eggs and larvae were monitored over time from digital photographs. FAA profiles of the eggs and larvae were measured in picomoles (pmol) of FAA/mg of eggs by HPLC. Newly fertilized eggs had a mean total FAA content of 21.72 ± 3.55 nmoles/egg (92.81 ± 9.71 nmoles/mg eggs). Leucine, valine, lysine, and isoleucine were the most abundant essential FAA comprising 35.9% of the total FAA. Alanine, serine, asparagine, and glycine were the most abundant non-essential FAA comprising 34.2% of the total FAA. At 24 h post-hatch (hph) the mean total FAA had decreased by 81% since egg fertilization. The bulk of the FAA decrease was between the time of hatch and 12 hph. Only 8.5 ± 1.5% of the initial concentration in fertilized eggs of isoleucine, 9.7 ± 2.5% of arginine, and 9.9 ± 2.0% of threonine remained at 12 hph. Among the non-essential FAA, alanine dropped the most by 12 hph with 4.6% of the concentration found in a recently fertilized egg remaining, while cysteine had increased 254.7 ± 26.2%. The yolk sac volume decreased rapidly in the first 12 hph and was further reduced 77.0 ± 2.5% from 12 to 24 hph. The oil globule depletion rate was a more linear decline from fertilized egg to 36 hph.

<正>本研究探讨了在育肥猪日粮中完全用水解羽毛粉代替豆粕的可行性。45头小母猪和45头去势公猪(每栏3头小母猪或3头去势公猪,每栏平均体重57.8±0.8kg)随机分5组,每组6个重复,饲喂1号育肥猪日粮。每栏

The objective of this study was to determine the possibility of replacing soybean meal (SBM) in finisher pig diets completely with hydrolyzed feather meal (FM). Forty-five gilts and 45 castrated males (57.8 +/- 0.8 kg of BW; 3 gilts or 3 castrated males/pen) were randomly assigned to 5 finisher-1 diets with 6 pens per diet. At an average pen BW of 81.0 +/- 1.4 kg, pigs were offered finisher-2 diets. Corn-SBM, finisher-1 and finisher-2 positive control (PC) diets were formulated to contain 6.1 and 4.7 g of apparent ileal digestible (AID) Lys/kg, respectively. Corn-FM negative control (NC) diets were formulated to be iso-N to the PC diets. The NC diets were supplemented with Lys and Trp (NRC; NC + Lys and Trp) to alleviate apparent deficiencies based on AID AA in FM reported by the 1998 NRC. In addition, the NC diets were supplemented further with the third limiting AA, Thr (40 + 3AA; NC + Lys, Trp, and Thr), and fourth and fifth limiting AA, His and Ile (40 + 5AA; NC + Lys, Trp, Thr, His, and Ile), based on the assumption that the apparent ileal digestibility of all indispensable AA in FM is 40%. Pigs had ad libitum access to feed and water. At the end of the study (112.1 +/- 1.8 kg), blood samples were collected from all pigs before slaughter. As expected, overall ADFI, AID Lys (representing indispensable AA) intake (LysI), ADG, and G: F were greater and BW gain: LysI (G: LysI) was less in pigs fed the PC diet than those fed the NC diet (P < 0.001). Pigs fed the NRC diet grew slower than those fed the PC diet (P = 0.004), and their G: LysI tended to be less than those fed the PC (P = 0.083) or the 40 + 3AA and 40 + 5AA diets (P = 0.094). Greater fat-free lean percentage (P = 0.005), fat-free lean gain (LG; P < 0.001), and LG: F (P < 0.001) were observed in pigs fed the PC diet compared with those fed the NC diet, but their LG: F or LG: LysI was similar to those fed the NRC diet. However, LG: F (P = 0.030) and LG: LysI (P = 0.028) were greater in pigs fed the 40 + 3AA and the 40 + 5AA diets than those fed the NRC diet. Pigs fed the 40 + 5AA diet tended to utilize AID Lys more efficiently for LG than those fed the 40 + 3AA diet (P = 0.068). Subjective meat color (P < 0.001), firmness (P = 0.004), and marbling (P < 0.001) scores were greater in pigs fed the 40 + 5AA diet than those fed the 40 + 3AA diet. Diets seemed to have no clear effect on the weight of liver, kidney, and heart or serum urea N and triacylglycerides. Pigs fed the PC diet had more serum albumin and total protein (P < 0.001), but less glucose (P = 0.031) and cholesterol (P < 0.001) than those fed the NC diet. Serum total protein was greater (P = 0.031) in pigs fed the 40 + 5AA diet than those fed the 40 + 3AA diet. The results indicated that the corn-FM diets were not as effective as the corn-SBM diet in supporting BW gain of finisher pigs. However, the results seemed to indicate that pigs fed the corn-FM diet supplemented with the necessary AA can utilize feed and AA for BW gain and lean gain as efficiently as those fed the corn-SBM diet. Further research is needed to explore fully the optimal AA supplementation strategy to effectively utilize FM for pig production.

This experiment was designed to determine the order of limiting amino acids (AA) beyond lysine (LYS) in a whey–skim milk–caseinate diet to be fed to low birth weight pigs. Initial pig weight was 1.71±0.30 kg (Rep. 1) and 1.62±0.11 kg (Rep. 2). The order was determined using a deletion assay. This was done using a positive control (PC) diet with AA concentrations and ratios to LYS at or above NRC recommendations, a negative control (NC) diet that reduced AA concentrations and ratios to LYS to 60% of the PC diet ratios, a supplemented negative control (Supp. NC) diet with AA supplemented to provide concentrations and ratios to LYS similar to the PC diet, and deletion diets which removed threonine (THR), tryptophan (TRP), sulfur amino acids (SAA), or phenylalanine (PHE) from the Supp. NC diet to levels in the NC diet. All diets contained 4.2 Mcal GE and 20.6 g LYS/kg DM. Diets were fed ad libitum (n=8/diet). Gain, intake, G:F, and PUN concentration were analyzed for effects of diet, replicate, and interaction. The SEM values were 7.33 g/d, 7.72 g DM/d, 0.02, and 0.33 mM, respectively, for diet main effect. Gain for animals fed PC (346 g/d), NC (269 g/d), and Supp NC (315 g/d) diets differed (P<0.05). Gain of pigs on all deletion diets was similar. The SAA deletion diet produced less gain (291 g/d, P<0.05) than Supp. NC diet. Intake was similar in pigs fed PC (306 g DM/d) and NC diets (310 g DM/d) and greater (P<0.05) than for pigs on all other diets. Feed efficiency decreased for pigs fed NC diet (0.87, P<0.05) compared to all other diets. Pigs fed SAA deletion diet had the greatest (P<0.05) PUN concentration (6.96 mM). Pigs fed THR deletion diet (5.70 mM) and PC diet (5.55 mM) had similar concentrations. Based on increased PUN concentration and decreased gain in pigs fed the SAA deletion diet relative to the Supp. NC diet, it is likely that SAA were next limiting. Threonine would likely be next limiting after SAA, also based on increased PUN concentrations.

A feeding trial was designed to examine the effects of copper sulfate pentahydrate (CuSO(4).5H(2)O) on the fatty acid composition and oxidative stability in muscle and adipose tissues of Boer x Spanish goat kids. Fifteen (n = 5 per treatment) goats were fed 0, 100, or 200 mg of supplemental Cu per day as copper sulfate for 98 d. The animals were slaughtered, and LM, s.c. adipose from the sternal region, and mesenteric adipose tissues were collected. Total lipids were extracted with chloroform:methanol (2:1), methylated and isolated via GLC from all tissues. The subsequent peaks were then positively identified by mass spectrometry. Thiobarbituric acid-reactive substances were measured also. In s.c. adipose, dietary Cu significantly decreased C14:0 (P = 0.03) and C16:0 (P = 0.01). In muscle, C15:0 (P = 0.03) was linearly increased by Cu. Dietary Cu supplementation did not influence oxidative stability in goat muscle or s.c. adipose. Copper supplementation at 200 mg/d resulted in a significant increase in malondialdehyde in mesenteric adipose (P = 0.01) compared with the 0 or 100 mg/d groups. These results indicate that lipid composition may differ from depot to depot and that depending on the depot, dietary Cu seems to elicit a variable response on the fatty acid composition.

Atmospheric ammonia (NH(3)) is a concern because of its environmental impact. The greatest contribution to atmospheric NH(3) comes from agricultural sources. This study quantified NH(3) volatilization from cattle defecation and urination on pasture under field conditions in Auburn, Alabama. Treatments consisted of beef feces, dairy feces, dairy urine, and a control. The experiment was conducted during four seasons from June 2003 to April 2004. Fresh feces or urine was applied onto grass swards, and NH(3) volatilization was measured up to 14 d after application using an inverted chamber method. Dairy urine was the only significant source of NH(3). Ammonia nitrogen (N) loss differed among seasons, ranging from 1.8% in winter to 20.9% during the warmer summer months. Cumulative volatilization was best described in this experiment by the equation % NH(3)-N loss = N(max) (1 - e(-ct))(i). The highest rate of NH(3) volatilization generally occurred within 24 h. This study suggests that NH(3) volatilization from cattle urine on pasture is significant and varies with season, whereas NH(3) volatilization from cattle feces is negligible.

Four methods of ranking horses on reactivity were evaluated and compared: isolation from conspecifics, presentation of a static novel stimulus, traversing a novel stimulus in a runway (isolation, novel stimulus and runway tests, respectively) and assigning subjective emotionality scores. In all tests, horses’ heart rates were recorded and behaviour was videotaped. To be considered a valid test of reactivity, at least one heart rate and one behavioural measurement in the test had to change significantly between treatments (tranquilizer administation versus sham tranquilizer administration), and behavioural measures had to be displayed in at least 75% of the trials. Forty horses performed each of the three tests daily on three different days in a switchback design. Horses were assigned randomly to a daily test sequence, which was maintained throughout the study. In the runway test, no significant difference in heart rate values in tranquilized and non-tranquilized horses was found, and no behavioural attribute was displayed in more than 52% of the trials; therefore it was rejected as a valid test of reactivity. Both isolation and novel stimulus tests produced valid measurements. Mean heart rate was the most precise physiological measure for these tests, and walking and defecation frequency were the most precise behavioural measures for novel stimulus and isolation tests, respectively. Mean heart rates on the novel stimulus and isolation tests were correlated (rs=0.79, P<0.01) indicating that these tests produced similar rankings based on physiological responses. However, behavioural measures ranked horses differently (rs=0.27, P<0.10) on the tests. Rank correlations between mean heart rates and behavioural measures were higher in the novel stimulus (rs=0.66, P<0.01) than the isolation test (rs=0.55, P<0.01), indicating that the novel stimulus test ranked horses based on either physiological or behavioural responses more similarly than did the isolation test. Therefore, the novel stimulus test was considered the more accurate evaluation of reactivity. Subjective emotionality scores were correlated moderately with mean heart rates (rs>0.33, P<0.01) from the novel stimulus and isolation tests and with walking scores (rs=0.47, P<0.01) from the novel stimulus test. Assignment of subjective emotionality scores was not as accurate as the novel stimulus or isolation tests in ranking horses for reactivity. Using physiological data alone, combining physiological and behavioural measurements or using more than one behavioural measurement in reactivity tests may reflect the reactivity of the horse better than a single behavioural measurement.

Dog (Canis familiaris L.) excreta may pollute the environment. However, little is known about the nature of canine feces and urine. A study was conducted to determine effects of age (young adult and geriatric) and diet (160, 240, or 320g crude protein (CP) kg(-1) feed) on element concentrations in female beagle excreta. Age had no significant effect on element concentrations in feces or urine. Increasing dietary CP significantly increased fecal carbon (C; P > F = 0.0001) and nitrogen (N; P > F = 0.0001) concentrations, but decreased C:N (P > F=0.0001). Canine fecal phosphorus (P) concentration was higher than typical values reported for feedlot cattle, broiler chickens, and swine produced in concentrated animal feeding operations. Fecal P concentration decreased when CP was increased from 160 (45.6g P kg(-1)) to 240 g kg(-1) (39.2g P kg(-1)), suggesting that dietary manipulation has potential to decrease P discharge to the environment.

Sixteen multiparous Jersey cows were assigned at calving to one of 4 dietary treatments. An 18% crude protein (CP) diet was fed as a total mixed ration through 30 d in milk (DIM), and beginning at 31 DIM a 9, 12, 15, or 18% CP diet was fed through 58 DIM (depletion). All cows were then fed the 18% CP diet until 84 DIM (repletion). Muscle biopsies were taken under local anesthesia at 49 and 84 DIM from the semitendinosus muscle. Milk production, DMI, and milk component contents were measured. Calpain and calpastatin contents of muscle taken at biopsy were evaluated using Western blotting techniques. Milk production and milk protein content were reduced during the depletion period by decreasing dietary protein. Diet had no effect on milk fat content or DMI. During repletion, DMI was affected by dietary treatment. Western blots of muscle extracts indicated no differences in calpain content at any stage of the experiment or in calpastatin content of muscle at 49 DIM. However, at 84 DIM, calpastatin (135 kDa) was lower or undetectable in cows fed either the 9 or 12% CP diets from 31 to 59 DIM. Bands for a 110-kDa degradation product of calpastatin were present in some cows fed the 9, 12, and 15% CP diets during the depletion period. Results indicate a change in skeletal muscle calpain/calpastatin proteolytic system during protein repletion following depletion with diets of less than 15% CP during early to peak lactation in dairy cows.

Effects of dietary ascorbyl-2-phosphate on immune function after a 210-km trip were measured in 18 Holstein heifers. After transport on d 0, 10 g of ascorbyl-2-phosphate each were added to the diets of 10 heifers, whereas eight heifers were fed a control diet. Plasma cortisol concentrations increased by an average of 25.6 microgram/ml on d 0 following transport, but by d 7 after transport had decreased to pretransport levels. Average daily gain was lower in heifers fed ascorbyl-2-phosphate from d 28 to 49 d after transport, but did not differ over the entire study. Feeding ascorbyl-2-phosphate maintained plasma ascorbate concentrations on d 7 post-transport, which decreased in control heifers. Plasma keyhole limpet hemocyanin antibody titers were significantly higher in control heifers from d 7 to 49. Mononuclear leukocyte proliferation responses were decreased on d 0 in lymphocytes stimulated by mitogens, with pokeweed mitogen-stimulated cells showing less of a response than cells stimulated by the other mitogens. In the absence of mitogens, dietary ascorbyl-2-phosphate increased basal 3H-methyl thymidine incorporation by cultured lymphocytes. Across diets and mitogens, lymphocytes treated with cortisol showed decreased 3H-methyl thymidine incorporation. Transportation acted as a stressor, as evidenced by the increased plasma cortisol levels at d 0 immediately after transport, but immunological effects were not apparent by d 7. Feeding ascorbyl-2-phosphate maintained plasma ascorbate concentrations on d 7, but had negative effects on immune responses posttransport.

The objectives were to determine effects of prepartum protein intake and dietary amino acid balance on production, adaptations in body fat and protein, amino acid concentrations, and, indirectly, body protein breakdown in early lactation. Multiparous Holstein cows (n = 42) were fed diets containing 11 or 14% crude protein with or without 20 g/d of methionine hydroxy analog for 21 d prepartum and then fed a common diet of 17% crude protein for 120 d postpartum, with or without 50 g/d of methionine hydroxy analog. Dry matter intake postpartum averaged 25.4 kg and milk production 41.6 kg. Cows fed the 14% CP diet ate 0.7 kg more dry matter and gave 1.7 kg more milk than those fed the 11% diet postpartum, but this difference was not significant. Cows fed methionine hydroxy analog prepartum lost less body protein from -14 to 60 d in milk. From d 60 to 120, body fat increased 8.5 and 11.5 kg for low and high protein groups and body protein increased 0.5 and 1.0 kg. Serum concentrations of branched chain amino acids fell 17% in the first few weeks postpartum, lysine fell 15%, histidine fell 16%, methionine increased 20%, and cysteine increased 30%. The ratio of serum 3-methylhistidine to creatinine was determined to indicate muscle protein degradation. An increase in this ratio at 7 d postpartum indicated increased body protein breakdown, there was no effect of prepartum ration. Increased protein intake prepartum may allow more feed intake and milk production postpartum, and supplementing a methionine analog on a ration already balanced in methionine by contemporary models may spare body protein.

Eighteen male English Pointers (2-4 years of age, 23.94+/-0.54 kg body weight) were allotted to three diet and two physical conditioning groups to evaluate the effect of level and source of dietary fat on the olfactory acuity of canine athletes subjected to treadmill exercise. Diet groups (6 dogs/diet) consisted of commercially prepared diets (minimum of 26% crude protein) containing 12% fat as beef tallow (A), 16% fat provided by equivalent amounts of beef tallow and corn oil (B), or 16% fat provided by equivalent amounts of beef tallow and coconut oil (C). This dietary formulation resulted in approximately 60% of the total fatty acid being saturated for diets A and C, while approximately 72% of the total fatty acids were unsaturated in diet B. One-half of the dogs within each dietary group were subjected to treadmill exercise 3 times per week for 30 min (8.05 km/h, 0% grade) for 12 weeks. All dogs were subjected to a submaximal exercise stress test (8.05 km/h, 10% slope for 60 min) every four weeks beginning at week 0. Olfactory acuity was measured utilizing behavioral olfactometry before and after each physical stress test. Non-conditioned (NON) dogs displayed a greater decrease (P<0.05) in olfactory acuity following exercise, while physically conditioned (EXE) dogs did not show a change from pre-test values. A diet by treatment interaction (P<0.10) was detected over the course of the study. NON dogs fed coconut oil had decreased odorant-detecting capabilities when week 4 values were compared with week 12 values. Feeding a diet that is predominately high in saturated fat may affect the odorant-detecting capabilities of working dogs. Additionally, these data indicate that utilization of a moderate physical conditioning program can assist canine athletes in maintaining olfactory acuity during periods of intense exercise.

Sixty-four pigs, 32 selected for lean growth efficiency and 32 controls selected randomly, were used to investigate the effect of genotype and realimentation diets on growth performance and carcass quality of pigs subjected to marginal dietary restrictions during the grower phase. When pigs weighed approximately 20 kg, 16 pens containing two gilts and 16 pens containing two castrated males were randomly assigned within genetic lines to grower diets and finisher diets in a 2×2×2 factorial arrangement of treatments. Grower diets contained 0.421 or 0.765 g lysine/MJ DE, whereas finisher diets contained 0.421 or 0.612 g lysine/MJ DE. Genotype had no effect on growth performance, but select line pigs had better carcass quality (P≤0.05) and seemed to utilize amino acids more efficiently for growth than control line pigs as indicated by lower blood urea nitrogen (P≤0.07). During the grower phase, pigs fed the high-amino acid grower diet grew faster and more efficiently (P<0.01) and had less ultrasound backfat (P<0.001) than those fed the low-amino acid diet. Although some grower×finisher diet interactions were observed, there was no indication that pigs subjected to early amino acid restrictions exhibited compensatory weight gain, or had different amino acid requirements in the subsequent phase. The rate of lean accretion was similar between pigs fed the low- and high-amino acid grower diets regardless of genotype, indicating that compensatory lean tissue growth may have occurred in pigs subjected to early amino acid restrictions. Furthermore, restricted pigs had better feed efficiency in the subsequent phase, which may have a positive impact on the environment by reducing the excretion of unutilized nutrients. Select line pigs fed the low-amino acid grower diet had lower overall weight gain compared with other groups (genotype×grower, P<0.001). The results imply that pigs selected for lean growth efficiency may be less tolerant of early amino acid restrictions, and offering a grower diet containing adequate amino acids might be important in optimizing overall growth performance.

Thirty-six adult female Beagles averaging 2 (young-adult) or 8 (geriatric) yr of age were used to assess the effects of graded levels of dietary protein (16, 24, or 32%) on endocrine-controlled regulation of whole-body protein turnover. Rates of whole-body protein synthesis (WBPS) and whole-body protein degradation (WBPD) were estimated using orally administered 15N-glycine and total excreta collection. Although N balance was similar for all dogs, N flux through the metabolic pool increased linearly (P < 0.05) as protein intake increased. Rates of WBPS, WBPD, or the difference between them were not influenced by age (P > 0.10). A quadratic increase (P < 0.05) in WBPS and WBPD was observed in response to dietary protein. Serum insulin-like growth factor-I (IGF-I), IGF-I-binding protein 3, and total IGF-I-binding proteins were higher (P < 0.05) in geriatric dogs than in young-adult dogs regardless of protein intake. These results indicate that dietary protein in excess of 16% may not be required to maintain N balance in young-adult and aging dogs despite the linear increase in N flux through the metabolic pool. Furthermore, age-induced changes in endocrine functionality may differ between dogs and other species.

Fifty-five multiparous Holstein dairy cows were used to evaluate the singular and combined effects of somatotropin and monensin treatments during the late dry period on postpartum metabolism and production.Treatments were 1) control (C); 2) injection of exogenous bovine somatotropin (bST); 3) TMR top dressed with 300 mg of monensin/day (M); and 4) monensin and somatotropin in combination (bST+M) during the last 28 days before expected parturition.A 500-mg subcutaneous injection of sustained release somatotropin was administered adjacent to the tail head at d -28 and -14 relative to expected calving.Diet and management were the same for all cows after parturition.Production and intake were measured daily until 63 d in milk.Milk composition, blood metabolites, and body weight and condition score were measured weekly.Prepartum glucose, nonesterified fatty acid, and blood urea nitrogen concentrations were not different among treatments.Cows on the M treatment tended to have greater dry matter intake postpartum than those on the C treatment and 30% lower plasma nonesterified fatty acid concentrations during wk 1 postpartum than all other treatments.Milk yield and milk fat yield were not different among treatments, but milk fat percent tended to be lower for the bST+M treatment than the C treatment.Changes in plasma amino acid concentrations were consistent with mobilization of skeletal muscle protein, possibly for use in gluconeogenesis.Results from this study provide evidence that prepartum feeding of monensin reduced plasma nonesterified fatty acid concentrations and may improve glucose metabolism of the periparturient dairy cow.