Technical note: a technique for multiple liver biopsies in neonatal calves

Effects of copper, zinc, and manganese source and inclusion during late gestation on beef cow-calf performance, mineral transfer, and metabolism

To determine effects of Cu, Zn, and Mn source and inclusion during late gestation, multiparous beef cows [n = 48; 649 ± 80 kg body weight (BW); 5.3 ± 0.5 body condition score (BCS)] were individually-fed hay and supplement to meet or exceed all nutrient recommendations except Cu, Zn, and Mn. From 91.2 ± 6.2 d pre-calving to 11.0 ± 3.2 d post-calving, cows received: no additional Cu, Zn, or Mn (control, CON), sulfate-based Cu, Zn, and Mn (inorganic, ITM) or metal methionine hydroxy analogue chelates (MMHAC) of Cu, Zn, and Mn at 133% recommendations, or a combination of inorganic and chelated Cu, Zn, and Mn (reduce and replace, RR) to meet 100% of recommendations. Data were analyzed with treatment and breeding group (and calf sex if P < 0.25 for offspring measures) as fixed effects, animal as experimental unit, and sampling time as a repeated effect for serum, plasma, and milk measures over time. Post-calving cow liver Cu was greater (P ≤ 0.07) in MMHAC compared with all other treatments. Calves born to RR had greater (P ≤ 0.05) liver Cu than ITM and CON, and MMHAC had greater (P = 0.06) liver Cu than CON. Liver Mn was less (P ≤ 0.08) for RR calves than all other treatments. Calf plasma Zn was maintained (P ≥ 0.15) from 0 to 48 h of age in ITM and MMHAC but decreased (P ≤ 0.03) in CON and RR. Gestational cow BW, BCS, and metabolites were not affected (P ≥ 0.13) by treatment, but gestational serum thiobarbituric acid reactive substances (TBARS) were greater (P = 0.01) for CON than MMHAC. Treatment did not affect (P ≥ 0.13) calf birth size, vigor, placental size and minerals, or transfer of passive immunity. Neonatal calf serum Ca was greater (P ≤ 0.05) for MMHAC than all other treatments; other calf serum chemistry and plasma cortisol were not affected (P ≥ 0.12). Pre-suckling colostrum yield, and lactose concentration and content, were greater (P ≤ 0.06) for MMHAC compared with ITM and RR. Colostral triglyceride and protein concentrations were greater (P ≤ 0.08) for RR than MMHAC and CON. Cow lactational BW and BCS, milk yield and composition, and pre-weaning calf BW and metabolism were not affected (P ≥ 0.13) by treatment. Lactational serum TBARS were greater (P = 0.04) for RR than CON at day 35 and greater (P ≤ 0.09) for MMHAC at day 60 than all other treatments. Source and inclusion of Cu, Zn, and Mn altered maternal and neonatal calf mineral status, but calf size and vigor at birth, passive transfer, and pre-weaning growth were not affected in this study.

Effect of supplemental trace minerals on standard and novel measures of bull fertility

Two studies were conducted to evaluate the effects of trace mineral supplementation on traditional and novel measures of bull fertility. In Experiment 1, 37 mature bulls received one of three dietary supplements daily for 71 d: 1) Supplement without Cu, Zn, and Mn (CON); 2) Supplement with Cu, Zn, and Mn sulfate (SULF); and 3) Supplement with basic Cu chloride, and Zn and Mn hydroxychloride (CHLR). In Experiment 2, 128 Angus or Angus-Hereford bull calves were maintained on a growing diet for 75 d (year 1) or 119 d (year 2) in Calan gate equipped pens without mineral supplementation. Bulls (n = 32 head/treatment) received one of four trace mineral supplements daily for 84 d: 1) Zn with no Cu (ZN), 2) Cu with no Zn (CU), 3) Cu and Zn (ZNCU), or 4) no Cu or Zn (CON). Bull fertility measures included a breeding soundness evaluation (BSE) and novel fertility measures conducted using flow cytometry. In mature bulls, final liver Zn concentration was positively correlated (P = 0.02) with sperm concentration (r = 0.31) and tended (P = 0.06) to be negatively correlated with acrosome damage (r = -0.39). Peripubertal bulls receiving ZNCU had greater ADG than bulls in the CU group (P = 0.05). Each BSE and novel fertility component improved from Day 0-84 in peripubertal bulls and were not affected (P > 0.10) by mineral supplementation. Bulls that received no supplement (CON) had greater (P < 0.01) percentage of sperm with distal midpiece reflex (6.9 vs 4.0% for CON and TM supplement, respectively) and Dag or Dag-like defect (2.6 vs 1.4% for CON and TM supplement, respectively) in their ejaculates. Sperm viability after 30 min of incubation were not affected by trace mineral supplementation, but after 3 h incubation, sperm viability tended to differ (P = 0.06) between treatments and tended to be less for CON bulls (48.5%) compared to ZNCU bulls (55.1%). Among contrast comparisons, trace mineral supplemented bulls had greater (P < 0.05) percentage of viable sperm at 3 h post collection and reactive oxygen resistant sperm than CON bulls. Addition of Zn to trace mineral containing Cu (ZNCU) improved (P < 0.05) percentage of sperm in the ejaculate with high mitochondrial energy potential and viable sperm with intact acrosome membrane. In summary, it appears the homeostasis mechanisms for bull trace mineral maintenance are extremely efficient and mineral supplementation of mature and peripubertal bulls did not have major improvements in any laboratory or chute-side measures of bull fertility, however bulls exposed to breeding or in environments with diet antagonists might respond differently.

Inductively coupled plasma mass spectrometry determination of hepatic copper, manganese, selenium, and zinc concentrations in relation to sample amount and storage duration

Trace mineral status is a critical component of bovine health. Impairment of physiological processes, caused by trace mineral toxicities or deficiencies, can be potential underlying factors of disease. Historically, the status of critical trace minerals, such as copper, manganese, selenium, and zinc, has been evaluated through the analysis of hepatic tissue. We assessed variation of these 4 elements between homogenized liver and samples of 0.02 g, 0.1 g, 0.5 g, and 1.0 g. We also evaluated concentration differences in copper, manganese, selenium, and zinc among samples stored under different durations. No differences in concentrations of copper, manganese, selenium, or zinc were observed among samples stored frozen for 3, 7, and 14 d post-collection. Statistical differences in concentrations of selenium and zinc were observed between 0.02-g biopsy samples and larger samples. Moisture content differed between 0.02-g biopsies and larger samples and over time. Results indicate that as little as 0.02 g of hepatic tissue dried to ~0.006 g is reliable for interpretation of trace mineral status and determination of toxicities and deficiencies in cattle pertaining to copper, manganese, selenium, and zinc, despite the small differences observed.

Ad libitum milk replacer feeding, but not butyrate supplementation, affects growth performance as well as metabolic and endocrine traits in Holstein calves

The enhanced growth performance of calves fed a higher plane of nutrition pre-weaning is well documented, and the effect of butyrate on the development of the gastrointestinal tract in calves has been evaluated. The aim of this study was to examine the synergistic effects of ad libitum milk replacer (MR) feeding and butyrate supplementation on growth performance and energy metabolism in calves. Sixty-four (32 male, 32 female) Holstein calves were examined from birth until wk 11 of life. Calves received MR either ad libitum (Adl) or restrictively (Res) with (AdlB+, ResB+) or without (AdlB-, ResB-) 0.24% butyrate supplementation. Colostrum and transition milk were fed in predefined amounts (Res or Adl) for the first 3 d postpartum. Ad libitum and restrictive MR feeding with or without butyrate was performed from d 4 until wk 8 of age. From wk 9 to 10, all calves were gradually weaned and were fed 2 L/d until the end of the trial. Concentrate (CON), hay, and water were freely available. Intakes of MR and CON were measured daily. Calves were weighed at birth and weekly thereafter. Blood was drawn on d 1 before the first colostrum intake; on d 2, 4, and 7; and weekly thereafter until the end of the study to measure plasma concentrations of metabolites and hormones. Liver samples were taken at d 50 and at the end of the study to determine gene expression related to glucose metabolism. Milk, MR, and total nutrient intake were greater, but CON intake was lower in Adl than in Res calves, resulting in a greater body weight, but partially lower gain to feed ratio in Adl than in Res. Plasma concentrations of glucose and insulin were higher during the ad libitum milk-feeding period, whereas plasma β-hydroxybutyrate was lower in Adl than in Res. Plasma concentrations of nonesterified fatty acids, lactate, total bilirubin, and cortisol were lower, but triglyceride and cholesterol concentrations were higher in Adl than in Res at specific time points. Feed intake, growth performance, and metabolic and endocrine changes were insignificantly affected by butyrate, and hepatic gene expression of enzymes related to endogenous glucose production was barely influenced by ad libitum MR feeding and butyrate supplementation. Intensive MR feeding indicated greater stimulation of growth and anabolic metabolism, but butyrate supplementation did not further improve postnatal growth or anabolic processes either in intensive or restrictive MR-fed calves.

Supplementation of corn dried distillers' grains plus solubles to gestating beef cows fed low-quality forage: II. Impacts on uterine blood flow, circulating estradiol-17β and progesterone, and hepatic steroid metabolizing enzyme activity

The objective of this study was to investigate the effects of supplementing dried distillers' grains plus solubles (DDGS) during late gestation on uterine blood flow (BF), circulating steroid hormones and hepatic steroid metabolizing enzymes, and calf and placental weights. Multiparous beef cows were randomly divided into a control group (CON; = 15) consuming a diet containing 90% corn stover and 10% corn silage (DM basis) for ad libitum intake and a treatment group (SUP; = 12) consuming the same diet and DDGS (0.3% of BW). Corn silage inclusion was increased to 30% as gestation progressed to meet increasing caloric requirements. Ipsilateral and contralateral uterine BF and cross-sectional area (CSA) of each uterine artery were measured by Doppler ultrasonography on d 180, 216, and 246 of pregnancy. Contralateral BF and CSA increased ( < 0.01) as gestation advanced. Ipsilateral BF and CSA was affected by a treatment × day of gestation interaction ( < 0.05). A main effect of treatment ( = 0.02) and day ( < 0.01) was observed for total BF; BF increased over time and SUP cows had greater BF than CON cows. Circulating concentrations of both progesterone (P4) and estradiol-17β (E2) were affected by an interaction of treatment and day ( < 0.01). Concentrations of circulating E2 steadily increased throughout the study and were greater in CON cows than in SUP cows by d 242. Concentrations of P4 also increased over time; P4 of CON cows was greater than that of SUP cows by d 242. Uridine 5'-diphospho-glucuronosyltransferase (UGT) and cytochrome P450 1A (CYP1A) activity increased with advancing gestation ( < 0.01). There was greater UGT activity ( < 0.05) and a trend for greater CYP1A activity ( = 0.06) in SUP cows than in CON cows. Activity of cytochrome P450 3A was greater ( < 0.01) in SUP cows and decreased ( < 0.05) with advancing gestation. Supplementing DDGS to cows fed low-quality forage during late gestation increased uterine BF but decreased circulating E2 and P4 concentrations and altered hepatic steroid metabolizing enzyme activity. It was anticipated that enzyme activity would reflect circulating hormone levels; however, our data suggests the observed increases in BF are not driven by alterations in hormone concentration. Therefore, further research is warranted to elucidate the underlying mechanisms.

The effect of follicular wave on fertility characteristics in beef cattle

The objectives of this experiment were to determine the effects of follicular wave (first or second) on diameter of the dominant follicle, concentrations of progesterone and estradiol and the hepatic enzymes that inactivate them, thickness of the endometrium, and pregnancy rates to AI. Beef heifers ( = 101) and cows ( = 106) were randomly assigned to 1 of 2 treatments: insemination to the first follicular wave (FFW) or insemination to the second follicular wave (SFW). Estrous cycles of females were synchronized to ensure appropriate timing for the treatments. The MIXED procedure of SAS was used for analysis. A similar proportion of females in each treatment responded to presynchronization; however, females in the FFW group ovulated in response to the first injection of GnRH of the CO-Synch protocol more frequently. Only females ( = 94) that properly responded to ovulation synchronization were included in further analyses. Cows in the FFW group tended ( 0.06) to have larger ovulatory follicles 36 h post-PGF of the CO-Synch protocol compared to cows in the SFW group (14.22 ± 0.42 and 11.83 ± 0.49, respectively), whereas heifers were similar between treatment groups. Three d prior to AI, circulating concentrations of progesterone were lesser ( 0.01) in females in the FFW (3.63 ± 0.80 ng/mL) than in the SFW (7.12 ± 0.83 ng/mL), whereas concentrations of estradiol tended ( 0.08) to be greater in those in the FFW (82.72 ± 6.48 pg/mL) than in the SFW (65.55 ± 6.74 pg/mL). Concentrations of cytochrome P450 1A in the liver were lesser ( 0.01) in females in the FFW than those in the SFW (0.68 ± 0.08 vs. 0.96 ± 0.06, respectively). Endometrial thicknesses were similar between treatments but were thicker ( < 0.0001) in cows (9.73 ± 0.24 mm) than heifers (7.22 ± 0.26 mm). When considering all females or only those that were properly presynchronized, pregnancy rates were similar between treatments. However, when evaluating females that ovulated to the assigned follicular wave, there was a treatment by parity interaction ( = 0.04) with heifers in the FFW having a lesser pregnancy rate (25.9%) than heifers in the SFW (72.0%) while cows in both treatment groups were intermediate (45.4% in FFW and 50.0% in SFW). The differences in concentrations of steroids between treatment groups may affect fertility of heifers; however, additional research is necessary.

A double-blind block randomized clinical trial on the effect of zinc as a treatment for diarrhea in neonatal Holstein calves under natural challenge conditions

Diarrhea is the leading cause of death in neonatal calves and contributes to major economic losses. The objective of this double-blind randomized clinical trial was to evaluate the effect of oral inorganic or organic zinc supplementation as a treatment for neonatal diarrhea in calves. Seventy nine 1 to 8 day old male Holstein calves on a California calf ranch were block randomized to one of 3 treatments within 24h from their first onset of diarrhea. Calves received a daily dose of either a placebo composed of 80 mg of zinc-free powder, 381.54 mg of zinc methionine (Met) (equivalent to 80 mg of zinc), or 99.69 mg of zinc oxide (ZO) (equivalent to 80 mg of zinc) in 2L of a zinc-free oral rehydration solution (ORS). Calves were treated once daily until normal fecal consistency or for a maximum of 14 days. Upon enrollment and exit, calves were weighed, and blood, feces, and liver biopsies were collected for trace mineral analysis. Fecal samples at enrollment and exit were tested for E. coli K99, Cryptosporidium spp., rotavirus and coronavirus. Pre-treatment liver zinc concentrations for the 71 calves in the placebo, zinc Met, and ZO treatment groups were 710.6 (SEM=147.7), 852.3 (SEM=129.6), and 750.7 (SEM=202.9)mg/kg dry weight (DW), respectively. Exit liver zinc concentrations for the calves in the placebo, zinc Met, and ZO treatment groups were 728.9 (SEM=182.9), 1141.0 (SEM=423.8), and 636.8 (SEM=81.5)mg/kg dry weight, respectively. Although statistically non-significant, there were clinically important findings identified for each of zinc Met and ZO treatments. Calves treated with zinc Met gained on average 40 g/day during a diarrhea episode compared to a weight loss of 67 g/day on average in the placebo-treated calves (Power 19.9%). Calves treated with ZO had 1.4 times higher hazard of clinical cure compared to calves in the placebo group (Power 5.3%). Calves that were fecal positive to cryptosporidium spp. at enrollment and treated with zinc Met had higher odds of testing negative at exit compared to placebo calves (Odds Ratio (OR)=16.0). In contrast, calves treated with ZO tended to recover (fecal score=1) one day earlier compared to calves treated with a placebo (8.5 d vs. 9.7 d). The current trial identified clinically important findings that warrant further research to investigate zinc's therapeutic effect for calf diarrhea.

Blood parameters in female Zandi lambs as affected by liver biopsy methodology

The aim of the present study was to investigate the normal blood parameters of Iranian fat-tailed sheep (Zandi) and their changes due to rapid liver biopsy technique with a tru-cut biopsy needle. In ten ewe lambs, blood samples were collected from jugular vein and biopsy needle was inserted through the dorsal one third of the 11th intercostal space, on the right hand side of the lambs and liver specimen was collected. Physical examinations were performed on alternate days during the experiment. Blood collection was done on both before (day 1) and after (day 17) the biopsy. All animals were slaughtered at day 17. Values were compared using paired t test. While biopsy did not make any significant changes in mean values of body temperature, heart rate, respiratory rate, PCV, WBC, neutrophil, lymphocyte, eosinophil, monocyte, total serum protein, AST, ALT, and serum calcium (p > 0.05), it made a significant difference on the values of ALP (p < 0.001), serum inorganic phosphate (p = 0.035), and magnesium (p = 0.013). Necropsy examination revealed the points of hitting the biopsy needles on the diaphragmatic surface of the livers, surrounded by a zone of intense hyperemia. Peritoneal adhesions accompanying with typical strands of fibrous connective tissue between diaphragmatic surface of the liver and adjacent abdominal wall were found in two cases.

Effect of photoperiod on hepatic growth hormone receptor 1A expression in steer calves

Photoperiod manipulation, specifically a long-day photoperiod (LDPP), increases milk production in lactating cattle. We have previously reported that the galactopoietic effect of LDPP is associated with an increase in circulating IGF-I, which seems to occur independently of changes in concentrations of GH, IGFBP-2, and IGFBP-3. This study tested the hypothesis that LDPP increases the expression of GH receptor (GHR) 1A messenger RNA (mRNA) in the liver. Two groups of Holstein steer calves (98 +/- 4 d old) were maintained indoors and exposed to LDPP (16-h light: 8-h dark; n = 6) or short-day photoperiod (SDPP; 8-h light: 16-h dark; n = 6) for 60 d. Calves were individually fed a grain- and alfalfa-based diet. Jugular blood samples were collected weekly and via cannula at 15-min intervals for a 4-h period on d 1, 26, and 55 of the study to monitor pulsatile hormone secretion. Serum was harvested and assayed for IGF-I, prolactin (PRL), and GH using RIA. Liver biopsies were obtained at 3-wk intervals to quantify changes in hepatic IGF-I and GHR 1A mRNA using real-time PCR. Steer BW increased during the study but did not differ between treatments. No differences in ADG or total DMI were observed. Relative to SDPP, calves on LDPP had higher (P < 0.05) serum IGF-I concentrations. Concentrations of PRL increased (P < 0.01) in calves exposed to LDPP compared with calves exposed to SDPP. Differences (P < 0.05) in pulsatile GH secretion were also detected. Hepatic IGF-I and GHR 1A mRNA were positively correlated with circulating IGF-I concentrations, and although both increased with time, they were not affected by photoperiod treatment. These results confirm that LDPP increases circulating concentrations of IGF-I, but this occurs independently of changes in IGF-I synthesis and GHR 1A mRNA expression in the liver. Therefore, our hypothesis that LDPP increases the expression of GHR 1A mRNA in the bovine liver is rejected.

Influence of dietary vitamin A content on serum and liver vitamin A concentrations and health in preruminant Holstein calves fed milk replacer

Evidence has suggested that the current requirement for vitamin A tabulated by the NRC [(approximately 3800 IU of vitamin A/kg of dry matter (DM)] for dairy calves fed liquid diets is too low. The objective of this study was to assess the effects of vitamin A content in milk replacers on serum and liver vitamin A concentrations, growth, and development of clinical signs of vitamin A deficiency in calves. Male Holstein calves were separated from their dams at birth and given standardized feedings of colostrum and milk replacer for 3 d. On d 4, calves were assigned to five groups and fed milk replacer containing 2300, 6200, 9000, 18,300, or 44,000 IU of vitamin A/kg of DM. Liver biopsies and serum samples were taken on d 4, 9, 15, 21, and 28 to monitor vitamin A concentrations. Weekly physical and neurological examinations were performed to monitor the development of deficiency signs. Fecal scores, body temperature, and the presence of nasal and ocular discharge were recorded daily. Liver vitamin A concentrations in calves allotted to diets with 2300 and 6200 IU of vitamin A/kg decreased from d 4 to 28. Calves fed 9000 IU of vitamin A/kg maintained liver stores, while those fed 18,300 and 44,000 IU of vitamin A/kg had significant increases in hepatic vitamin A. A strong negative association existed between incidence of hyperthermic temperatures and vitamin A concentration in the diet; calves fed 2300 IU of vitamin A/kg had approximately three times more hyperthermic readings than did calves fed other treatments. A strong negative association also existed between fecal score and concentration of vitamin A in the diet; calves fed diets containing low vitamin A concentration had a higher incidence of high fecal scores (more watery) than did calves fed diets with higher vitamin A concentrations. Although slight differences were detected in serum retinol concentration, growth performance and incidence of ocular and nasal discharges were not different among treatment groups. Our data indicate that vitamin A concentrations of less than 9000 IU/kg of DM in milk replacers result in declining liver vitamin A stores in preruminant calves. Using the human Dietary Reference Intakes as a model for calculating the requirement, we recommend that the vitamin A requirement for preruminant calves should be increased to 11,000 IU of vitamin A/kg of DM.