Clove bud (Syzygium aromaticum) improved blood and hepatic antioxidant indices in laying hens receiving low n-6 to n-3 ratios.

This study was carried out to investigate the effects of different levels of clove bud (Syzygium aromaticum) powder and vitamin E on serum lipid profile, enzyme activities and antioxidant indices, as well as hepatic biochemical and histological alterations in laying hens receiving different n-6 to n-3 ratios. A total of 160 laying hens, 43 weeks of age, were allotted to 8 experimental diets with 5 cages of 4 birds each. Dietary treatments consisted of two ratios of n-6 to n-3 (16.71 and 2.35), three levels of clove bud (0.0, 2.0 and 4.0 g/kg) and a high vitamin E level (200 mg/kg, as a positive control in each level of n-6 to n-3 ratio) in a 2 × 4 factorial arrangement during 70 days of the experiment. Results showed that a decline in the n-6 to n-3 ratio led to a reduction in serum cholesterol concentration (p < 0.05) and an increase in serum HDL content (p < 0.05). Additionally, decreasing n-6 to n-3 ratio and increasing clove bud level caused a remarkable decline in serum aspartate aminotransferase (p < 0.05 and p < 0.001) and alanine aminotransferase (p < 0.05 and p < 0.05) enzyme activities. Furthermore, total antioxidant capacity (p < 0.05 and p < 0.001) as well as serum vitamin E concentration (p < 0.05 and p < 0.001) was decreased and enhanced by low n-6 to n-3 ratio diets (LRD) and clove bud powder respectively. Decreasing the n-6 to n-3 ratio lowered hepatic lipid (p < 0.05) and glycogen contents (p < 0.01) as well as tissue integrity (p < 0.05), and raised liver MDA concentration (p < 0.001), markedly. Nevertheless, increments in clove bud content led to a reduction (p < 0.01) in liver relative weight (p < 0.05) and hepatic fat vacuole numbers. In general, the best synergistic responses on modulating of blood lipids and serum enzyme activities were observed when the highest level of clove bud was supplemented in the diets with low n-6 to n-3 ratio. Likewise, antioxidant indices were improved by administration of dietary clove bud powder although feeding fish oil was observed to elevate the susceptibility of blood and hepatocytes to lipid peroxidation.

Effect of early feed restriction on physiological responses, performance and ascites incidence in broiler chickens raised in normal or cold environment.

Intensive selection of broilers for faster growth and better feed efficiency resulted in greater susceptibility to metabolic disorders such as ascites syndrome, which is one of the major causes of mortality and economic loss in broiler industry. Whereas cool temperature is one of the primary triggers for ascites, early feed restriction (FDR) significantly alleviates its incidence and mortality. However, little is known about effects of FDR, cold environmental temperature and their interaction on physiological responses in broiler chickens. For this purpose, 320 one-day-old male broilers were divided into two treatment groups of Ad libitum (Ad) and feed restricted (FR) with eight pen replicates each. Chickens in FR group underwent feed access limitation from days 7 to 14 of age. On day 21 half of the birds (four pens) in each group exposed to the cold temperature (CT) and the other half (four pens) continued at normal temperature (NT). Average daily feed intake, average daily weight gain and feed conversion ratio (FCR) were measured at days 7, 14, 21, 28 and 42. At 39 and 46 days of age two chicks with a BW around the pen average were selected from each pen and slaughtered after collecting blood samples. Then, relative weight of internal organs and right ventricle weight per total ventricle weight (RV : TV) ratio were calculated. Compared with NT group, CT birds had higher daily feed intake and FCR (P<0.05) from day 28 to 42. Cumulative ascites mortality in CT chickens was higher (P<0.001) than NT chicks. Within the CT group, ascites mortality in FR chickens was reduced (P<0.001) to 1.25% compared with 8.75% in Ad chicks. Birds in CT group had significantly (P<0.05) thicker right ventricle and greater relative weight of heart, hematocrit and triiodothyronine concentration. However, none of these parameters were affected by FDR. Under cold stress conditions, FDR reduced activity of alanine aminotransferase and aspartate aminotransferase (P<0.05). Serum triglyceride, cholesterol, high-density lipoprotein and total protein were not influenced by either temperature or feeding regimen. In conclusion, these findings suggest that FDR reduces ascites incidence mainly by allowing better development of internal organs, which helps them to cope with the high metabolic pressure and suffer less damage.

Effects of cilostamide and/or forskolin on the meiotic resumption and development competence of growing ovine oocytes selected by brilliant cresyl blue staining.

The relevance of low developmental competence of in vitro-matured oocyte to the incomplete/delayed cytoplasmic maturation, and the heterogeneity of retrieved oocytes is well established in several species. A short phase of prematuration culture was used to allow better oocyte cytoplasmic maturation. The preselection of growing and fully grown oocytes has been proposed to improve developmental competency. This study investigated the effects of phosphodiesterase type 3-specific inhibitor, cilostamide, and adenylate cyclase activator, forskolin, on the resumption of meiosis and developmental competence of growing ovine oocytes selected by brilliant cresyl blue (BCB) staining. Results indicate that cilostamide, forskolin, and their combination significantly (P < 0.05) increased the percentage of growing (BCB-) oocytes maintained at the germinal vesicle stage. However, only forskolin significantly (P < 0.05) increased the yield and quality of blastocysts derived from BCB- oocytes compared with non-BCB-treated oocytes. We conclude that a short prematuration culture with forskolin may improve the in vitro developmental competency of growing oocytes in ovine.

A physiological, rather than a superovulated, post-implantation environment can attenuate the compromising effect of assisted reproductive techniques on gene expression in developing mice embryos.

Assisted reproductive techniques (ARTs) may perturb the pre-/peri-conception microenvironments, which subsequently threaten the health of offspring. This study aimed to investigate the effects of superovulation, vitrification, in vitro culture, and embryo transfer on the expression of epigenetic modulators, imprinted genes, and pluripotency markers in expanded blastocysts and Day-9.5 (D9.5) concepti. Results revealed that 53.4% (8/15) and 86.7% (13/15) of genes in the fetus and placenta, respectively, have similar patterns of transcription in all D9.5 concepti, despite the perturbed mRNA expression observed at the blastocyst stage for each embryo-production technique. These observations indicate a counterbalancing of the abnormal expression pattern analyzed at the blastocyst stage during post-implantation development, particularly when the uterus of a naturally synchronized foster mother is employed. Superovulation resulted in the most abnormal expression patterns compared to other treatment groups, although these same blastocysts were able to develop in a synchronized uterus. Thus, superovulation creates a hormonal environment that negatively affected gene expression and impairs fetal growth more adversely during post-implantation development than other ART protocols, such as in vitro culture, vitrification, or embryo transfer-although each did contribute negatively to the implantation and development process. Together, these results may have implications for treating infertility in humans.

Dose-responses of zinc-methionine supplements on growth, blood metabolites and gastrointestinal development in sheep.

The effects of zinc-methionine (Zn-Met) supplementation on growth, blood metabolites and gastrointestinal development were investigated in two experiments with sheep. The objective of Experiment 1 was to determine the effects of Zn-Met supplementation on hormones and metabolites involved in growth and energy balance regulation, while Experiment 2 aimed to determine the effects of Zn-Met on feed intake, body weight, gastrointestinal development and liver glycogen concentration in lamb. The animals were assigned to groups with different concentrations of dietary Zn-Met (0, 0.4, 0.8 and 1.2 g/day) in both experiments. In Experiment 1, feeding different doses of Zn-Met increased plasma insulin-like growth factor 1 (IGF-1) concentration, but it linearly decreased plasma growth hormone (GH). No differences were observed in blood cortisol, insulin and glucose concentrations among the treatments. In Experiment 2, addition of Zn-Met to the diets did not lead to changes in the body weights of the lambs. Both average daily gain and dry matter intake (DMI) increased linearly with increasing concentrations of dietary Zn-Met. Lambs receiving Zn-Met showed higher liver glycogen concentrations than the control. While significant increases were observed in the villus height and crypt depth in the duodenum and jejunum as a result of Zn-Met supplementation, no change was detected in blood glucose concentrations (p > 0.05). Our findings suggest that dietary Zn-Met may improve growth, energy balance and gastrointestinal development in sheep.

Effect of prepartal and postpartal dietary fat level on performance and plasma concentration of metabolites in transition dairy cows.

The objective of this study was to determine the effects of 2 levels of dietary fat (low and high) offered during the prepartal and postpartal periods on dry matter intake (DMI), plasma concentration of metabolites, and milk yield and composition. Twenty-four Holstein dry cows were assigned on d 21 relative to expected parturition date to 1 of 4 treatments in a 2×2 factorial arrangement of 2 levels of fat fed during the prepartal period and 2 levels of fat fed during the postpartal period: prepartal low fat and postpartal low fat (LF-LF), prepartal low fat and postpartal high fat (LF-HF), prepartal high fat and postpartal low fat (HF-LF), or prepartal high fat and postpartal high fat (HF-HF). Prepartal and postpartal LF diets contained no fat supplement. Prepartal HF diets contained 1.60% calcium salts of soybean oil. The proportion of calcium salts of soybean oil was increased to 1.70% of DM for the first 21 d of lactation and to 2.27% of DM from d 21 to 56 of lactation in the HF diet. Diets were fed for ad libitum intake from d 21 before calving until d 56 of gestation. Prepartal DMI was lower for cows fed the HF diet compared with those fed the LF diet (12.6 vs. 16.2kg/d). Postpartum, cows fed the HF-HF and HF-LF diets had, respectively, the lowest and highest DMI, although no significant differences existed between HF-LF and LF-LF. Net energy intake was higher for cows fed the postpartal HF diets compared with those fed the LF diets. Prepartal fat level had no effect on net energy intake. Cows offered the prepartal HF diet had higher milk yield when offered the postpartal LF diet compared with those offered the postpartal HF diet and no effect of the postpartal fat level was detected when cows were fed the prepartal LF diet. Milk composition was similar among treatments. Plasma cholesterol concentration postpartum was higher for cows fed the prepartal LF diet than for those fed the prepartal HF diet (5.16 vs. 3.74mmol/L) and postpartal fat level had no effect. Prepartal diet had no significant effect on postpartal plasma triglyceride concentration but the postpartal HF diet increased triglyceride and low-density lipoprotein concentrations compared with the postpartal LF diet. In conclusion, switching from a high to a low fat proportion in the postpartal diet may alleviate the negative effects of a high proportion of fat in the prepartal diet as shown by increased feed intake and milk production during the first 56 d of lactation.

Effects of feeding roasted safflower seeds (variety IL-111) and fish oil on dry matter intake, performance and milk fatty acid profiles in dairy cattle.

UNLABELLED: Safflower seed has the highest concentration of linoleic acid among 80 oilseeds but little information exists on the effective use of SS for lactation cows. It was hypothesised that a diet supplemented with an Iranian SS variety (IL-111) in combination with fish oil (FO) would result in higher concentrations of trans-18:1 (including vaccenic acid) and conjugated linoleic acids in milk fat than feeding an unsupplemented control diet. Our objective was to determine the effects of feeding diets containing: (i) CONTROL: (C); (ii) 25 g of roasted SS IL-111 (RSS); (iii) 20 g FO and (iv) 25 g RSS + 10 g FO (RSS + FO) per kilogram of dietary DM on feed intake, ruminal fermentation, milk production and fatty acid profile. Eight multiparous Holstein cows were used in a replicated 4 × 4 Latin square design study. The experiment had four periods of 21 days. Milk Fat percentage was lower (p < 0.01) with FO supplementation and averaged 19.0 and 21.5 g/kg milk with FO and RSS + FO compared with 30.3 and 32.5 g/kg with C and RSS. Feed intake also was lower (p < 0.01) with FO vs. C (23.1 vs. 24.5 kg/day) but feeding RSS resulted in greater feed intake compared with other treatments (26 kg/day). Despite lower feed intake with FO, milk production did not change from controls but feeding RSS + FO resulted in greater milk yield than controls (42.6 vs. 39.3 kg/day). Ruminal pH was greater (p < 0.01) in cows fed FO than other treatments. Supplemental FO alone or in combination with RSS resulted in dramatic increases (p < 0.01) in c9,t11-18:2 in milk fat (12.7 and 13.2 g/day vs. 5.8 and 7.02 with C and RSS). It was surprising to note that 25 g/kg RSS can improve feed intake.

Chromium supplementation and substitution of barley grain with corn: effects on metabolite and hormonal responses in periparturient dairy cows.

Thirty-two multiparous Holstein cows were used to investigate the effects of chromium-l-methionine (Cr-Met) supplementation and dietary grain source on metabolic indices throughout the periparturient period. Cows were fed a total mixed ration with the concentrate portion based on ground barley (barley based diet, BBD)--or ground corn (corn-based diet, CBD) from 21 days before anticipated calving through 28 days after calving. The Cr-Met was supplemented at dosages of 0 or 0.08 mg of Cr/kg of metabolic body weight throughout the experiment. Thus, treatments were in a 2 (Cr-Met) × 2 (grain sources) factorial arrangement. Plasma glucose, non-esterified fatty acids, triglyceride, very low-density lipoprotein, blood urea nitrogen (BUN), insulin, glucagon, cortisol and insulin-like growth factor-I (IGF-I) concentrations were not affected by chromium supplementation on calving day (d 0). However, there was a trend for decreased ß-hydroxybutyrate (BHBA) and increased cholesterol on d 0 in cows fed the Cr supplemented diet. On d 21 postpartum (wk 3 p.p.), plasma glucagon concentration tended to be greater in cows fed the Cr supplemented diet. However, other plasma metabolite and hormone measures were not affected by Cr supplementation in wk 3 p.p. There was no effect of grain source on d 0 plasma metabolic and endocrine measures. In wk 3 p.p., a significant difference was found only for plasma concentration of glucagon that was higher for cows fed the BBD compared with the CBD. There was an interaction of Cr-Met supplementation and grain source in wk 3 p.p. plasma concentration of BUN to decrease in CBD and increase in BBD, supplemented with Cr-Met. No Cr by grain interactions were observed for other plasma metabolic variables on d 0 and in wk 3 p.p. These results indicate that Cr-Met supplementation and substituting barley grain with corn throughout the transition period have only moderate effects on metabolic and endocrine parameters.

Chromium improves production and alters metabolism of early lactation cows in summer.

Metabolic demands of early lactation introduce enormous challenges to dairy cows when coincided with environmental stresses. The objective of this study was to determine effects of a chromium (Cr) supplement on feed intake and blood indicators of nutrient metabolism in early lactation cows in summer. Fifteen Holstein cows at 38±6 days in milk were grouped based on parity and randomly assigned to three supplemental doses of 0, 0.05 and 0.10 mg Cr/kg of BW(0.75) . Cows received a basal mixed ration with a forage to concentrate ratio of 57.7:42.3, twice daily at 09:00 and 16:00 h for 9 weeks. The first 2 weeks were for adaptation, and the following 7 weeks were for weekly sampling and data collection. The Cr supplement (a Cr-methionine product with 10% Cr and 90% Met from a compound containing one atom of Cr and three molecules of Met) was mixed with 100 g of ground corn and top dressed with the morning feed. The average ambient temperature-humidity index was 77.7 units during the study. Dry matter intake increased from 21.8 to 24.2 and 23.7 kg/day when 0.05 and 0.10 mg Cr/kg BW(0.75) was provided respectively. Milk output of energy, fat, protein and total solids increased by providing Cr at 0.05 mg but not 0.10 mg/kg BW(0.75) . Both doses of Cr increased milk protein content, but the higher Cr dose reduced feed efficiency compared with control. While rectal temperature and body condition score were unaffected, cows receiving 0.05 mg and not 0.10 mg Cr/kg BW(0.75) tended to have greater respiration rate than control cows. Blood insulin and non-esterified fatty acids concentrations and the insulin to glucagon ratio decreased, and serum albumin increased when cows received 0.05 mg of Cr/kg BW(0.75) . Blood glucose, glucagon, insulin-like growth factor-1, total protein, globulins, urea, BHBA, triglycerides, cholesterol, cortisol, progesterone, and high- and very low-density lipoproteins were not affected. Therefore, supplemental Cr supply at 0.05 and 0.10 mg/kg BW(0.75) improved feed intake, only at 0.05 mg/kg BW(0.75) increased milk secretion, and mainly at 0.05 mg/kg BW(0.75) altered peripheral nutrient metabolism in early lactation Holstein cows under high ambient temperatures.

IGF-I gene polymorphism, but not its blood concentration, is associated with milk fat and protein in Holstein dairy cows.

We estimated the allele and genotype frequencies of IGF-I/SnaBI gene polymorphism and the concentration of this protein in Holstein dairy cows. We also examined the association with milk yield (305-day milk yield) and milk components (fat and protein percentage, and 305-day milk protein and fat yield). Blood IGF-I levels were measured and genotyping was performed on 250 Holstein cows of four different herds. In the association studies, traits of interest were analyzed using the GLM procedure of SAS; means of the IGF-I level among genotypes were compared by the LSMeans test. The AB and AA genotypes were the most (0.583-0.661) and least (0.083-0.192) frequent in the herds, respectively; the frequency of the BB genotype ranged from 0.201 to 0.333. The frequency of the A allele ranged from 0.375 to 0.495, while the frequency of the B allele ranged from 0.504 to 0.625, being the dominant allele. The mean level of IGF-I was 107 +/- 22 ng/mL for all groups, without any significant correlation with the production traits. Association of IGF-I/SnaBI genotypes with percentage of fat and protein in the milk was relatively high (P < 0.1 and P < 0.05, respectively); the AB genotype was superior to AA and BB genotypes. We concluded that this marker should be considered for milk component selection in Holstein dairy cattle.

Gene expression of tumour necrosis factor and insulin signalling-related factors in subcutaneous adipose tissue during the dry period and in early lactation in dairy cows.

Gene expression of adipose factors, which may be part of the mechanisms that underlie insulin sensitivity, were studied in dairy cows around parturition. Subcutaneous fat biopsies and blood samples were taken from 27 dairy cows in week 8 antepartum (a.p.), on day 1 postpartum (p.p.) and in week 5 p.p. In the adipose tissue samples, mRNA was quantified by real-time reverse transcription polymerase chain reaction for tumour necrosis factor alpha (TNFα), insulin-independent glucose transporter (GLUT1), insulin-responsive glucose transporter (GLUT4), insulin receptor, insulin receptor substrate 1 (IRS1), insulin receptor substrate 2 (IRS2), regulatory subunit of phosphatidylinositol-3 kinase (p85) and catalytic subunit of phosphatidylinositol-3 kinase. Blood plasma was assayed for concentrations of glucose, ß-hydroxybutyric acid, non-esterified fatty acids (NEFA) and insulin. Plasma parameters followed a pattern typically observed in dairy cows. Gene expression changes were observed, but there were no changes in TNFα concentrations, which may indicate its local involvement in catabolic adaptation of adipose tissue. Changes in GLUT4 and GLUT1 mRNA abundance may reflect their involvement in reduced insulin sensitivity and in sparing glucose for milk synthesis in early lactation. Unchanged gene expression of IRS1, IRS2 and p85 over time may imply a lack of their involvement in terms of insulin sensitivity dynamics. Alternatively, it may indicate that post-transcriptional modifications of these factors came into play and may have concealed an involvement.

Effects of dietary egg yolk antibody powder on growth performance, intestinal Escherichia coli colonization, and immunocompetence of challenged broiler chicks.

The present study aimed to investigate the effects of dietary supplementation of different levels of specific IgY (sIgY) and nonspecific IgY (nsIgY) egg yolk antibody powder on growth performance, immune functions, and intestinal morphology of Escherichia coli O78:K80-challenged broiler chicks. Lyophilized antibody isolated by the water-dilution method was obtained from the eggs of laying hens hyperimmunized with E. coli O78:K80. A total of 392 broiler chicks were randomly assigned to 7 dietary treatments with 4 replicates of 14 chicks (7 males and 7 females) each. Before offering the experimental diets, 7-d-old broiler chicks (except the negative control) were challenged orally with 0.5 mL (10(9) cfu/mL) of E. coli O78:K80 suspension. The challenge was continued for an additional 7 d from d 14 to 21 with 1.0 mL of a late log phase culture (10(9) cfu/mL) until the level of E. coli in feces reached 10(5) cfu/g. The 6 challenged groups received a basal diet supplemented with 0 (as positive control), 0.1, 0.2, or 0.4% (wt/wt) sIgY from eggs of immunized hens or levels of 0.2 or 0.4% (wt/wt) nsIgY from eggs laid by the nonimmunized hens. The negative control group was fed with the same unsupplemented diet. Oral infection caused an increase in ileal E. coli enumeration, total blood leukocytes, heterophil:lymphocyte ratio, the concentration of serum and intestinal secretory IgA, and the numbers of jejunal goblet cells and lamina propria lymphatic follicles. After 3 wk of feeding, the levels of 0.2 and 0.4% sIgY and 0.4% nsIgY had the most suppressive effects (P < 0.01) on the ileal E. coli enumeration and secretory IgA concentration. However, serum IgA concentration was slightly decreased only at the presence of 0.4% sIgY and nsIgY. Dietary supplementation with at least 0.2% sIgY decreased (P < 0.05) the circulating heterophil:lymphocyte ratio. Inclusion of both sIgY and nsIgY increased the villus height:crypt depth ratio and decreased the jejunal goblet cells and lamina propria lymphatic follicle numbers, with the most pronounced effects assigned to sIgY-supplemented groups. The best feed conversion ratio was obtained when the dietary inclusion of at least 0.2% sIgY continued for 3 wk. The present results indicate that dietary administration of at least 0.2% sIgY for 3 wk improved the intestinal health indices and immunological responses of broiler chicks orally challenged by E. coli O78:K80.

Increased colostral somatic cell counts reduce pre-weaning calf immunity, health and growth.

Our objective was to study the relationships between colostral somatic cell counts (SCC, a criterion for mastitis severity at parturition) and early calf growth, blood indicators of immunity, and pre-weaning faecal and health states. Sixty-nine Holstein cows were assigned to three groups of greater (n = 21, 5051 × 10(3)), medium (n = 38, 2138 × 10(3)) and lower (n = 10, 960 × 10(3)) colostral SCC (per ml) in a completely randomized design. Calves received 2 l of colostrum on day 1, and jugular blood was sampled at birth, at 3 h after the first colostrum feeding and at 42 days of age for immunoglobulin G (IgG) measurements. Calves were fed transition milk from their dams until 3 days of age and whole milk from 4 to 60 days of age twice daily at 10% of body weight. Health status and faecal physical scores were recorded daily for 42 days. Increased colostral SCC was associated with increased serum IgG at parturition. Colostral pH increased and fat percentage decreased linearly with the rising SCC. Feeding colostrum with greater SCC was associated with reduced serum IgG concentrations at 3 h after first colostrum feeding, greater incidences of diarrhoea and compromised health status during the first 42 days of age, and reduced weaning weight gain, but had no effects on calf body length and withers height. Colostral volume and percentages of protein, lactose, solids-non-fat, total solids and IgG were comparable among groups. Results suggest a role for SCC, as an indicator of mastitis and colostral health quality, in affecting calf health. As a result of the novelty of calf health dependence on colostral SCC found, future studies to further characterize such relationships and to uncover or rule out possible mediators are required before colostral SCC could be recommended for routine on-farm use in managing dry cow and calf production.

In vitro comparison of egg yolk-based and soybean lecithin-based extenders for cryopreservation of ram semen.

Substitution of egg yolk with soybean lecithin may reduce hygienic risks in extenders. Though a few studies have been performed on the effect of soybean lecithin in bull, to date evaluation of ram semen in vitro fertility after cryopreservation with use of soybean lecithin has not been studied. This study assessed the effect of 1% or 2% (wt/vol) soybean lecithin (L1 or L2) or 15% or 20% (vol/vol) egg yolk (E15 or E20) supplemented with 5% or 7% glycerol (G5 or G7) in a Tris-based medium for cryopreservation of ram (Oviss arries) semen. Although no significant difference was observed in pattern of capacitation, the best results in terms of sperm motility, viability postthaw, and cleavage rates were observed with L1G7 (51.9+/-4.8%, 48.1+/-3.5%, and 79.6+/-3.9%, respectively) and E20G7 (51.8+/-2.9%, 46.7+/-4.0%, and 72.9+/-6.4%, respectively). Our results also showed that 1% lecithin and 20% egg yolk was superior to 2% lecithin and 15% egg yolk. In terms of cleavage rate, 7% glycerol was superior to 5% glycerol. No significant difference was obtained between groups in terms of blastocysts rate per cleaved embryo. Therefore, we concluded that the optimal concentration of lecithin and egg yolk is 1% and 20%, respectively, along with 7% glycerol. In addition, our results suggest that lecithin can be used as a substitute for egg yolk.

Chromium supplementation and substitution of barley grain with corn: Effects on performance and lactation in periparturient dairy cows.

Thirty-two multiparous Holstein cows were used to investigate the effects of chromium-l-methionine (Cr-Met) supplementation and dietary grain source on performance and lactation during the periparturient period. Cows were fed a total mixed ration consisting of either a barley-based diet (BBD) or a corn-based diet (CBD) from 21 d before anticipated calving through 28 d after calving. The Cr-Met was supplemented at dosages of 0 or 0.08 mg of Cr/kg of metabolic body weight. The study was designed as a randomized complete block design with 2 (Cr-Met levels) x 2 (grain sources) factorial arrangement. There was no Cr effect on prepartum dry matter intake (DMI) or postpartum DMI, body weight (BW), net energy balance, and whole tract apparent digestibility of nutrients. Prepartum DMI as a percentage of BW tended to increase with Cr-Met. Supplemental Cr-Met tended to increase milk yield whereas milk protein percentage decreased. Pre- and postpartum DMI, BW, net energy balance, milk yield, and milk composition were not affected by substituting ground barley with ground corn. The addition of Cr-Met increased prepartum DMI and tended to increase postpartum DMI of the BBD but not the CBD. The change in prepartum DMI was smaller when the BBD was supplemented with Cr-Met but remained unchanged when the CBD was supplemented with Cr-Met. Yields of crude protein and total solids in milk and prepartum digestibility of DM and organic matter tended to increase when Cr-Met was added to the BBD but remained unchanged when added to the CBD. Periparturient cows failed to respond to the grain source of the diet, whereas they showed greater response in milk yield to diets supplemented with Cr-Met. In conclusion, the present results demonstrate that the beneficial effect of Cr-Met supplementation during the periparturient period to improve feed intake may depend on the grain source of the diet.

Growth, weaning performance and blood indicators of humoral immunity in Holstein calves fed supplemental flavonoids.

The primary objective was to test the hypothesis that flavonoids mediate immune response and affect calf performance. Twenty Holstein calves [7 +/- 2 days age; 41.4 +/- 0.7 kg body weight (BW)] were randomly assigned to four treatments of (i) no; (ii) low (7.3 x 10(-5) g/kg BW); (iii) medium (7.3 x 10(-4) g/kg BW); and (iv) high (3.6 x 10(-3) g/kg BW) doses of flavonoids intake in a completely randomized design. Calves received the treatments as a tablet until weaning or a daily intake of 680 g starter. After weaning, calves received no supplemental flavonoids and monitored until 120 days of age. The flavonoids were extracted from propolis. Treatments did not affect body length, wither height and the severity of scours. At week 5 of age, BW was higher when calves fed the high compared to the low dose of flavonoids. At week 6, calves fed the high dose of flavonoids had higher BW than those fed no or low doses of flavonoids. The serum immunoglobulin G (IgG) concentrations remained lower at the first 3 weeks of the experiment when calves received the low but not the high doses of flavonoids. At week 4, both medium and low doses of flavonoids moderated serum IgG. At week 8, the medium and high but not the low doses of flavonoids lowered serum IgG. At week 6, calves fed high and medium flavonoids doses had lower blood immunoglobulin M (IgM) than control calves. Results suggest that flavonoids affect the humoral immune response and can improve growth in young calves. This response depended on calf age. Future studies are needed to further evaluate the premise that dietary forages or the main source of flavonoids are helpful for a less stressful weaning in the modern calf raising.

Effects of short dry periods on performance and metabolic status in Holstein dairy cows.

To evaluate effects of different dry period lengths on milk yield, milk composition, and energy balance of dairy cows, 122 multiparous and primiparous Holstein dairy cows were used in a completely randomized experimental design with 56-, 42-, and 35-d dry period lengths. Actual dry period lengths for respective treatments (TRT) were 56 +/- 5.1 d, 42 +/- 2.1 d, and 35 +/- 2.7 d. Overall, cows in the 42- and 56-d TRT gained more body condition than those in 35-d TRT during the dry period; however, postpartum body condition score did not change substantially among the TRT. Although from 3 to 210 DIM, differences were not detected in the milk yield of multiparous cows between the 35- and 56-d TRT, primiparous cows in the 35-d TRT produced less milk than those in 56-d TRT. In primiparous cows, the milk production at wk 9, 10, and 11 of lactation was lower in the 35-d compared with the 56-d TRT. Primiparous cows in the 35-d compared with the 56-d TRT produced less milk protein. In the 35-d TRT, serum triglyceride concentration was greater in primiparous cows than in multiparous cows during the peripartum period. Among primiparous cows, those in the 56-d TRT had greater concentrations of nonesterified fatty acids than those in the 35-d TRT during the peripartum period. No significant differences were observed in concentrations of serum glucose, insulin, and insulin-like growth factor-I during early lactation among TRT. There was also no difference among TRT for incidence of metabolic disorders. Thus, this study indicates that shortening the dry period to 35 d may be beneficial in multiparous and overconditioned cows, but not in primiparous cows.

Pharmacological characterisation of oxytocin binding sites in the ovine pineal gland.

Both oxytocin (OT) and [Arg8]vasopressin (AVP) are found within the ovine pineal gland and may function to modulate melatonin secretion. However, the receptors which mediate the actions of these peptides have yet to be characterised. Preliminary studies of ovine pineal microsomal cell membranes showed binding of [3H]OT (79+/-9 fmol/mg) 10 times greater than binding of [3H]AVP (8+/-3 fmol/mg). Saturation studies using either [3H]OT or the selective OT receptor ligand [125I]d(CH2)5[Tyr(Me)2,Thr4,Orn8,Tyr-NH2(9)]-vasotocin (OTA) revealed high affinity, single site kinetics (Kd = 1.72+/-0.32 nM; Bmax = 68+/-18 fmol/mg). Binding of [3H]AVP was more effectively displaced by OT than AVP, suggesting that binding may be due to cross-reaction with the OT binding site. Displacement of [3H]OT using a range of selective agonists and antagonist analogues revealed pharmacological characteristics similar to [3H]OT binding sites in the ovine and rat uterus. These data show that the ovine pineal expresses a high density of OT binding sites which may participate in the regulation of melatonin secretion.

Characterisation of vasopressin V1a binding sites in the ovine olfactory bulb.

In the ewe, [Arg8]vasopressin (AVP) release into the olfactory bulb (OB) modulates transmitter release necessary for the induction of olfactory memory. [3H]AVP binding to a microsomal preparation of ovine OB revealed saturable binding to a single class of high affinity sites (Kd = 2.03 +/- 0.18 nM). The density of binding sites was significantly greater in the lamb than ewe, but did not vary across the adult oestrous cycle. Displacement using AVP analogues showed that their relative affinities for the ovine V1a receptor were identical to the rat hepatic V1a receptor. These data demonstrate a single class of AVP binding sites in the ovine OB and the first pharmacological characterisation of the ovine V1a receptor.