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To determine factors affecting colostrum yield and quality, data from 148 cow-calf pairs over 6 experiments were combined. In each experiment, single rear quarter colostrum yield was obtained postcalving but pre-suckling. Colostrum IgG was determined by ELISA, and colostrum lactose, triglycerides (as a measure of total fat), and protein were determined by colorimetric analyses. Total IgG and nutrients were calculated as the concentration multiplied by single-quarter yield. Calf birth weight and expelled placental dry weight were also collected post-calving. Mixed linear models (experiment as a random effect) were used to determine the effects of dam age (primiparous: 2 yr, young: 3 to 4 yr, mature: ≥ 5 yr), dam peripartum body condition score (BCS; thin: < 5, moderate: 5 to 5.99, fleshy: ≥ 6), and calf sex on colostrum yield (single-quarter colostrum weight) and quality. Pearson correlation coefficients were also determined for colostrum yield with dam pre-calving body weight (BW), calf birth weight, calf birth weight relative to dam BW, whole placental dry weight, and gestation length. Mature dams had the greatest (P ≤ 0.03) and primiparous dams had the least (P ≤ 0.001) colostrum yield and total lactose. Colostrum from primiparous dams had greater (P = 0.03) IgG concentration than mature and greater (P ≤ 0.001) protein concentration than young and mature. Mature dams had greater (P ≤ 0.02) total IgG, total protein, and total triglycerides compared with both primiparous and young. Colostrum yield was less (P ≤ 0.04) for thin than moderate and fleshy dams. Total IgG was unaffected (P = 0.11) by dam BCS; however, thin dams had greater (P ≤ 0.04) IgG concentration than moderate and fleshy. Lactose concentration and total lactose were less (P ≤ 0.02) in colostrum from thin compared with moderate dams. Protein concentration was greater (P = 0.001) in thin than moderate dams, but thin dams had less (P ≤ 0.02) total protein compared with moderate and fleshy. Dam BCS did not affect (P ≥ 0.59) colostrum triglyceride concentration or total triglycerides. Colostrum yield and quality were not affected (P ≥ 0.22) by calf sex. Pre-calving dam BW was positively correlated with colostrum yield (r = 0.46, P < 0.001). Colostrum yield was also positively correlated with calf birth weight (r = 0.31, P < 0.001) and whole placental dry weight (r = 0.26, P = 0.007), but tended to be negatively correlated with calf birth weight relative to dam BW (r = -0.14, P = 0.09). Gestation length had no relationship (P = 0.31) with colostrum yield. Overall, colostrum yield and quality are negatively affected in young and thin beef dams. In addition, both dam and calf weight have positive relationships with colostrum yield, likely mediated by endocrine action associated with placental size. [ABSTRACT FROM AUTHOR]

Data from 9 calving experiments were used to investigate relationships of dam, calf, and colostrum factors with passive transfer in beef calves. Serum was collected at 48.33 ± 1.25 (SD) h of age for 313 calves, and single rear quarter colostrum yields were determined pre-suckling for dams of 117 calves. Serum and colostrum IgG concentrations were determined by ELISA. Relationship of serum IgG with colostrum variables was determined using Pearson correlation coefficients. Serum IgG was positively correlated (P ≤ 0.002) with colostrum IgG (r = 0.47) and protein (r = 0.45) concentrations and colostrum total IgG (r = 0.28) but tended to be negatively correlated (r = -0.17, P = 0.06) with colostrum yield. Based on passive transfer thresholds in the literature, 3 calves (0.96%) had < 8 mg/mL serum IgG, 16 calves (5.1%) < 16 mg/mL, and 43 calves (13.7%) had < 24 mg/mL. For this analysis, calves with serum IgG < 24 mg/mL at 48 h were considered to have failure of passive transfer (FPT). Continuous variables (dam BW and calf size, 48-h serum chemistry panel, and time to stand) were compared for FPT versus non- FPT calves using a mixed model with FPT class (fixed effect) and experiment (random effect). Calves with FPT had less (P ≤ 0.03) circulating triglycerides, glucose, calcium, magnesium, total protein, globulin, and gamma-glutamyl transferase but greater (P ≤ 0.001) circulating non-esterified fatty acids, sodium, chloride, and total bilirubin than non-FPT. Effects of categorical variables on calf 48-h serum IgG were determined using separate mixed models with variable (fixed) and experiment (random). Primiparous dams gave birth to calves that had less (P = 0.05) serum IgG at 48 h than multiparous dams. Calves born to moderate dams (BCS = 5) had less (P = 0.007) serum IgG than those born to fleshy dams (BCS ≥ 6) and tended to have less (P = 0.08) serum IgG than calves born to thin dams (BCS < 5). Calf sex, calving season, calving difficulty score, and vigor score at 10 min did not affect (P ≥ 0.19) serum IgG. Relationships of calf 48-h serum IgG with continuous variables was also determined using Pearson correlation coefficients, and only r ≥ 0.20 or ≤ -0.20 are reported. Serum IgG was positively correlated (P ≤ 0.005) with 48-h serum total protein (r = 0.75), globulin (r = 0.76), gamma-glutamyl transferase (r = 0.32), and potassium (r = 0.20). Serum IgG was negatively correlated (P < 0.001) with gestation length (r = -0.22) and 48-h serum albumin (r = -0.43), sodium (r = -0.24), and total bilirubin (r = -0.27). Overall, beef calves in this dataset generally had successful passive transfer that was associated with several dam, calf, and colostrum factors. [ABSTRACT FROM AUTHOR]

Fall-calving Hereford-SimAngus heifers [single-sired; body weight (BW): 451 ± 28 (SD) kg; body condition score (BCS): 5.4 ± 0.7] bred to a single sire were individually-fed 100% (control; CON; n = 12) or 70% (nutrient restricted; NR; n = 13) of estimated metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from d 160 of gestation to calving. Post-calving, all females were fed to meet lactational nutrient requirements until weaning. From d 1 to 147 of lactation, dams were individually fed chopped tall fescue hay and supplemented in Calan gates to constrain diets of calves to milk only. After d 147, dams and calves were managed as a group in drylots, and calves could access the tall fescue hay offered to their dams. Bull calves (CON; n = 8; NR; n = 9) were castrated at 176 ± 3 (SD) d of age to represent a later pre-pubertal growth stage that is indicative of post-pubertal testis size. The epididymis and pampiniform plexus were removed, and calipers were used to determine the length and perpendicular widths of each testis. Testis weight was recorded, and testis volume was determined by water displacement in a graduated cylinder. Testis parenchyma was fixed in neutral buffered formalin for histological analyses. Seminiferous tubule diameter was measured on perpendicular diameters of 40 randomly chosen tubules with a visibly round cross-section. Data were analyzed with late gestational nutritional plane and calving date as fixed effects. Birth weight of bull calves was not affected (P > 0.99), but we previously reported that late gestational nutrient restriction decreased (P ≤ 0.04) milk production by 15% during the first 147 d of lactation. By d 63 of age, bull calves born to previously NR dams weighed less (P = 0.03) than bull calves born to CON dams. Body weight remained different (P ≤ 0.04) until castration, at which point bull calves born to previously NR dams weighed 14% less (P = 0.02) than bull calves born to CON dams. Average testis diameter was less (P = 0.03), and average testis length tended to be less (P = 0.07) for calves born to previously NR dams. Paired testes weight and volume were less (P ≤ 0.05) for calves born to previously NR dams, but testes weight relative to calf BW and average seminiferous tubule diameter were not affected (P ≥ 0.20) by late gestational nutritional plane. In the current study, pre-pubertal bull calves born to NR dams had decreased testis size, but it is difficult to delineate if this is a direct effect of gestational undernutrition on fetal development or its indirect effect on post-weaning development due to decreased milk production. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the influence of melatonin supplementation in pregnant beef cattle grazing toxic, endophyte-infected tall fescue (E+) on post-calving dam body weight (BW), milk production, and preweaning growth of steer calves. Multiparous cows were artificially inseminated with sex-sorted semen (Y chromosome-bearing sperm) from a single Red Angus sire and maintained on pastures free from E+ fescue prior to the start of the treatment period. Pregnant cows were assigned to one of three treatment groups with two replications per treatment: non-toxic, novel endophyte-infected (NE+) tall fescue without melatonin supplementation (NE+/NM; n = 15), E+ fescue with melatonin supplementation (E+/M; n = 16), and E+ fescue without melatonin supplementation (E+/NM; n = 18). The treatment period was over 70 d between May and July (d 147 ± 1 to 217 ± 1 of gestation). A commercially available feed was mixed with melatonin (100 µg/kg BW) or without melatonin and hand-fed to each cow daily. At the conclusion of the treatment period (56 ± 18 d before parturition), cattle were moved to a single group and maintained on pastures free from E+ fescue for the remainder of the study. Dams and steer calves were weighed at d 0, 28, 56, 84, 112, 140, and 168 relative to calving (d 0 = calving). Four-hour milk yields on d 28 ± 3 and d 56 ± 3 were used to estimate daily milk volume and weight. Dam and calf BW were analyzed using the MIXED procedure of SAS specific for repeated measures with treatment, time, and the interaction as fixed effects and replicate as random. Calf birth weight, dam milk volume, and dam milk weight were analyzed using the MIXED procedure of SAS with treatment as a fixed effect and replicate as random. On d 28, estimated daily milk volume and weight were decreased (P < 0.05) in E+/NM dams relative to NE+/NM dams. On d 56, estimated daily milk volume and weight were decreased (P < 0.03) in E+/NM and E+/M dams relative to NE+/ NM dams. There was an effect of time for dam and calf weights (P < 0.01). There was a treatment by time interaction for calf body weight, with calves born to E+/NM dams having decreased body weight relative to calves born to NE+/NM and E+/M dams from d 112 to d 168 (P = 0.02). There were no other effects of treatment, time, or the interaction (P > 0.05). These data suggest melatonin supplemented to pregnant crossbred multiparous beef cows grazing endophyteinfected tall fescue during mid-late gestation may increase preweaning growth of steer calves. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the effects of peripartum supplementation of a methionine hydroxy analogue (MHA) to primiparous, spring-calving beef females on dam and progeny performance. Angus heifers (n  = 60) were blocked by expected parturition date, stratified by body weight (BW) and body condition score (BCS), and randomized to 1 of 15 pens. Pens were randomly assigned to 1 of 3 dietary treatments: a basal diet supplemented with 0 (M0), 15 (M15), or 30 (M30) g/animal/d of MHA (provided as MFP feed supplement, Novus International Inc. St. Charles, MO). Diets were fed from 45 ± 13 (SD) d pre-calving through 81 ± 13 d postpartum (DPP), after which all cow–calf pairs were managed as a single group on pasture until weaning (199 ± 13 DPP). Dam BW, BCS, and blood samples were taken at 6 predetermined timepoints. Progeny data were collected at birth, 2 intermediate timepoints, and at weaning. Milk samples were collected for composition analysis at 7 ± 2 DPP and at 55 ± 5 DPP. Serial progesterone samples were analyzed to establish resumption of cyclicity, and ultrasonography was performed at 55 ± 5 DPP to evaluate ovarian function. Cows were bred via artificial insemination at 82 ± 13 DPP and subsequently exposed to bulls for a 55-d breeding season. Pen was the experimental unit, and preplanned orthogonal contrasts were tested (linear effect and M0 vs. M15 + M30). Dam BW and BCS were not affected by treatment (P  ≥ 0.29) throughout the study. Week 1 milk fat concentration increased linearly (P  = 0.05) and total solids tended to increase linearly (P  = 0.07) as MHA increased; however, no other milk components were affected (P  ≥ 0.16). Treatment did not affect (P  ≥ 0.16) dam reproductive parameters or progeny growth from birth until weaning. Post-calving, circulating methionine equivalents tended to linearly increase (P  = 0.10) with increasing MHA supplementation. At breeding, plasma urea N linearly decreased (P  = 0.03) with increased supplementation of MHA, and plasma non-esterified fatty acids were less (P  = 0.04) in MHA-supplemented dams compared with dams receiving no MHA. Maternal circulating glucose, glutathione peroxidase, and thiobarbituric acid-reactive substances were not affected (P  ≥ 0.15) by treatment at any point. These data indicate that peripartum supplementation of MHA may increase milk fat composition shortly after calving, but MHA supplementation did not improve progeny growth or dam reproductive performance in the current study. [ABSTRACT FROM AUTHOR]

Fall-calving primiparous beef females [body weight: 451 ± 28 (SD) kg; body condition score: 5.4 ± 0.7] were individually-fed either 100% (control; CON; n = 13) or 70% (nutrient restricted; NR; n = 13) of metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from day 160 of gestation to parturition. Calves were reared naturally by their dams and monitored for latency times from birth to first sternal recumbency, attempt to stand, and stand; vigor scores were assigned at 2, 5, 10, and 20 min of age. Rectal temperatures and jugular blood were obtained at 0 (pre-suckling), 6, 12, 24, and 48 h of age, and blood chemistry, hematology, cortisol, and insulin were determined. Data were analyzed with fixed effects of late gestational nutritional plane (single data point) or nutritional plane, hour, and their interaction (data over time, repeated measures). Calving date was a fixed effect; calf sex was included when P < 0.25. We previously reported that late gestational nutritional plane did not affect gestation length or calf size at birth, but calving assistance and fetal malpresentation occurred more often in NR. Nutritional plane did not affect (P = 0.65) duration of parturition, but calves born to NR dams had slower times to attempt to stand (P = 0.09), slower times to stand (P = 0.02), and poorer 20 min vigor scores (P = 0.05). Serum immunoglobulin G and A concentrations at 48 h were greater (P ≤ 0.03) for NR calves. Rectal temperature of NR calves was less (P = 0.02) at 0 h, but greater (P = 0.04) at 24 h compared with CON. Circulating glucose, non-esterified fatty acids, triglycerides, cortisol, and insulin were not affected by nutritional plane (P ≥ 0.18). Total protein and globulin from 6 to 48 h were greater (P ≤ 0.02) in NR calves. Calves from NR dams had greater (P ≤ 0.08) gamma-glutamyl transferase at 6, 12, and 48 h. Serum aspartate aminotransferase was greater (P ≤ 0.07) from 0 to 24 h and creatine kinase was greater (P ≤ 0.04) from 6 to 24 h in NR calves. At 0 h, potassium was greater (P = 0.03) in NR calves. Calves born to CON had greater chloride (P = 0.08; main effect), sodium (P ≤ 0.09) from 0 to 48 h, and anion gap (P = 0.02) at 6 h. Hematocrit from 6 to 24 h and red blood cells and hemoglobin at 6 and 12 h were greater (P ≤ 0.09) in CON calves. These data indicate that nutrient restriction during late gestation resulted in less vigorous calves with more indicators of trauma in early life. [ABSTRACT FROM AUTHOR]

Fall-calving primiparous crossbred beef females [body weight (BW): 451 ± 28 (SD) kg; body condition score (BCS): 5.4 ± 0.7] were allocated by fetal sex and expected calving date to receive either 100% (control; CON; n = 13) or 70% (nutrient restricted; NR; n = 13) of metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from day 160 of gestation to calving. Heifers were individually-fed chopped poor quality hay and supplemented to meet targeted nutritional planes based on estimated hay intakes. Dam BW, BCS, backfat, and metabolic status were determined pre-treatment, every 21 d (BW and metabolic status) or 42 d (BCS and backfat) during gestation, and post-calving. At birth, calf BW and size were measured, and total colostrum from the most full rear quarter was collected pre-suckling. Data were analyzed with nutritional plane, treatment initiation date, and calf sex (when P < 0.25) as fixed effects. Gestational metabolites included day and nutritional plane × day as repeated measures. During late gestation, CON dams gained (P < 0.01) maternal (non-gravid) BW and maintained (P ≥ 0.17) BCS and backfat, while NR dams lost (P < 0.01) maternal BW, BCS, and backfat. Circulating glucose, urea N, and triglycerides were less (P ≤ 0.05) in NR dams than CON at most late gestational timepoints after treatment initiation. Circulating non-esterified fatty acids were greater (P < 0.01) in NR dams than CON. Post-calving, NR dams weighed 63.6 kg less (P < 0.01) and were 2.0 BCS less (P < 0.01) than CON. At 1 h post-calving, NR dams had less (P = 0.01) plasma glucose and tended to have less (P = 0.08) plasma triglycerides than CON. Nutrient restriction did not affect (P ≥ 0.27) gestation length, calf birth weight, or calf size at birth. Colostrum yield was 40% less (P = 0.04) in NR dams than CON. Protein and immunoglobulin concentrations were greater (P ≤ 0.04), but free glucose and urea N concentrations were less (P ≤ 0.03), in colostrum of NR dams than CON. Colostrum total lactose, free glucose, and urea N were less (P ≤ 0.03) in NR dams than CON, but total protein, triglycerides, and immunoglobulins were not affected (P ≥ 0.55). In summary, beef heifers experiencing late gestational nutrient restriction prioritized partitioning nutrients to fetal growth and colostrum production over maternal growth. During undernutrition, fetal and colostral nutrient demands were largely compensated for by catabolism of maternal tissue stores. [ABSTRACT FROM AUTHOR]

To determine effects of dam parity on perinatal nutrient availability in beef cattle, data and samples were collected from 18 primiparous and 35 multiparous spring-calving Sim-Angus dams and their calves. Time to stand was recorded and neonatal vigor assessed. Jugular blood was collected from a subset of calves at 0 (post-standing and pre-suckling) 6, 12, 24, 48, and 72 h of age, and blood chemistry panels were completed. Expelled placentas were dissected, dried, and weighed. Prepartum maternal circulating glucose, non-esterified fatty acids (NEFA), triglycerides, and urea N were analyzed. All statistical models included the fixed effect of dam parity, and calf sex (when P ≤ 0.25) was included for calf and placental variables. Effects of sampling hour, and parity × hour were included for calf metabolites over time using repeated measures. Multiparous dams had greater body weight prepartum (P < 0.001) but similar (P = 0.25) body condition score. Maternal circulating urea N and triglycerides were greater (P ≤ 0.05) in multiparous dams pre-calving. Calves born to primiparous dams weighed 10% less (P ≤ 0.04) at birth with smaller (P ≤ 0.01) heart and abdominal girths. Cotyledonary, intercotyledonary, and total placental masses were less (P ≤ 0.05) for primiparous dams. Dam parity did not affect (P ≥ 0.58) calf time to stand, vigor score at 10 min, or rectal temperature. Serum glucose was greater (P = 0.03) at 0 h but less (P ≤ 0.04) at all other hours in calves from primiparous dams. Calves from primiparous dams had greater (P ≤ 0.02) serum NEFA at 6, 12, and 24 h although plasma triglycerides were greater (P < 0.001) at 6 h. Calves from primiparous dams had greater (P ≤ 0.04) serum urea N at 12 h and creatinine at 12 and 24 h. Plasma insulin was greater (P ≤ 0.04) in calves from multiparous dams at 12, 48, and 72 h, but parity did not affect (P ≥ 0.18) serum total protein or plasma cortisol. Serum aspartate aminotransferase was greater (P ≤ 0.04) at 6 and 24 h, creatine kinase was greater at 24 h, and gamma-glutamyl transpeptidase was less (P ≤ 0.04) at 6, 12, and 24 h, for calves from primiparous dams. Calves born to primiparous dams had greater (P ≤ 0.02) total bilirubin and direct bilirubin at 12 and 24 h. Data indicate that calves born to first-parity heifers had decreased perinatal nutrient availability, resulting in reduced fetal and placental growth, as well as greater energy reserve mobilization and metabolic indicators of stress as neonates. [ABSTRACT FROM AUTHOR]

To determine the effect of calving season on perinatal nutrient availability and neonatal beef calf vigor, data were collected from 4 spring- (average calving date: February 14; n = 203 total) and 4 fall- (average calving date: September 20; n = 179 total) calving experiments. Time to stand was determined as minutes from birth to standing for 5 s. After birth, calf weight and size (length, heart and abdominal girth, and cannon circumference) were recorded. Jugular blood samples and rectal temperatures were obtained at 0, 6, 12, and 24 h postnatally in 6 experiments and at 48 h postnatally in Exp. 2 to 8. Data were analyzed with fixed effects of season (single point) or season, hour, and their interaction (over time, using repeated measures). Experiment was a random effect; calf sex was included when P ≤ 0.25. Within calving season, correlations were determined between calf size, vigor, and 48-h serum total protein. Fall-born calves tended to have lighter (P = 0.09) birth weight and faster (P = 0.05) time to stand than spring-born calves. Season did not affect (P ≥ 0.18) gestation length, other calf size measures, or 48-h serum total protein. Fall-born calves had greater (P ≤ 0.003) rectal temperature at 0, 24, and 48 h postnatal. Spring-born calves had greater (P ≤ 0.009) circulating glucose at 0 h, serum non-esterified fatty acids at 0 and 6 h, and plasma triglycerides at 0, 6, 12, and 48 h. Fall-born calves had greater (P ≤ 0.03) sodium from 6 to 48 h and magnesium from 0 to 24 h of age. Phosphorus was greater (P ≤ 0.02) at 6 and 12 h of age in spring-born calves. Spring-born calves had greater (P ≤ 0.04) aspartate aminotransferase at 12 and 24 h and creatine kinase at 0 and 12 h of age. Fall-born calves had greater (P ≤ 0.03) albumin, calcium, and chloride, had lower (P ≤ 0.03) bicarbonate and direct bilirubin, and tended to have greater (P = 0.10) anion gap (all main effects of calving season). Calf birth weight had a weak positive relationship (P ≤ 0.03) with 48-h serum total protein and time to stand in fall-born, but not spring-born, calves. Overall, fetal growth was restricted and neonatal dehydration was increased by warm conditions for fall-born calves, but vigor and metabolism were negatively affected by cold conditions in spring-born calves. These data suggest that calving season influences perinatal nutrient availability, which may impact the transition of beef calves to postnatal life. [ABSTRACT FROM AUTHOR]

Multiparous Rambouillet ewes (n = 32) were allocated in a completely randomized design to determine if rumen-protected L-arginine (RP-Arg) supplementation during mid- and late gestation would 1) alter maternal carotid artery hemodynamics and 2) affect circulating amino acids associated with arginine metabolism in dams from day 54 of gestation to parturition and in their offspring from birth to 54 d of age. Ewes were assigned to one of three treatments from day 54 ± 3.9 to parturition: control (CON; 100% nutrient requirements), restricted (RES; 60% of CON), and RES plus 180 mg RP-Arg•kg BW-1•d1 (RES-ARG). Ewes were penned individually in a temperature-controlled facility. Carotid artery hemodynamics was measured via Doppler ultrasound at day 50 and 130 of gestation. Maternal serum was collected at day 54 and 138 of gestation and at parturition. At parturition, lambs were immediately removed from their dams and reared independently. Lamb serum samples were collected at birth and 1, 3, 7, 33, and 54 d of age. Pulsatility index was the only hemodynamic measurement altered by dietary treatment, where day 130 measurements were greater (P ≤ 0.04) for RES and RES-ARG compared with CON. The change in pulsatility index was greater (P < 0.01) for RES compared with CON but tended to be intermediate (P ≥ 0.12) for RES-ARG. Maternal serum Arg, Cit, and Asp at day 138 were greater (P < 0.01) for CON compared with RES and RES-ARG; serum Orn at day 138 was greater (P = 0.04) for CON compared with RES. Maternal serum Cit at parturition was greater (P ≤ 0.03) for CON and RES-ARG compared with RES. Offspring serum Arg was affected by a maternal treatment by day of age interaction (P = 0.03), where at day 3, CON and RES-ARG had greater (P ≤ 0.03) serum Arg concentrations than RES, and at day 54, RES-ARG was greater than (P = 0.002) CON and RES was intermediate and did not differ from (P ≥ 0.09) CON and RES-ARG. Offspring serum Orn and Cit were less (P ≤ 0.03) for RES and RES-ARG compared with CON. Results indicate that distal tissue blood perfusion decreased due to maternal RES, and RES-ARG was able to improve perfusion but not to the level of CON ewes. Further, maternal RP-Arg altered offspring Arg and related amino acid concentrations during the postnatal period. [ABSTRACT FROM AUTHOR]

Successful intrauterine growth relies on adequate placental nutrient transfer capacity and is determined by placental size, placental morphology, uteroplacental blood supply, nutrient transporter abundance, and the nutrients available in maternal circulation. The majority of bovine fetal growth occurs during late gestation and must be accompanied by similar exponential increases in uteroplacental development to allow for necessary nutrient delivery. Competition for nutrients in young females between maternal growth and satisfying pregnancy, lactation, and maintenance requirements is still poorly understood. Our current work investigated the relationships between maternal, fetal, and uteroplacental factors and the impacts of late gestational nutrient restriction on prenatal nutrient delivery to the calf. Analysis of 113 full-term expelled placentas revealed that primiparous dams and dams in thin body condition had smaller placentas than their older or fleshier counterparts, suggesting the addition of growth requirements or exhausted nutrient reserves limited placental and fetal development. Calf size at birth and placental weight were positively correlated among all females, but it is still unknown which controls and signals for the growth of the other. Uterine blood flow measured during late gestation was positively correlated with calf birth weight; however, uterine blood flow and placental weight were only positively correlated closer to parturition at 40 and 20 d before calving. Additionally, contralateral uterine blood flow may have a disproportionately greater contribution to placental and fetal growth as it more closely resembled total blood flow associations than did ipsilateral. In 2 experiments, primiparous females fed 70% of energy and protein requirements during late gestation lost body weight and condition, had less metabolites in circulation, and had lower maternal heart rates than those fed to meet requirements. In Exp. 1, nutrient restricted dams had less contralateral placental growth, yet total uterine blood flow and placental weight were maintained and ensured fetal growth similar to control offspring. In Exp. 2, nutrient restriction reduced calf birth weight by 15%. Fetal growth perturbations were largely driven by a 17% reduction in placental size along with less nutrients available from maternal circulation, independent of a concomitant decrease in uterine blood flow. At 48 h of age, calf visceral organs were smaller due to nutrient restriction, but asymmetrical growth allowed for growth of the brain, lungs, and bone to be spared. Ongoing analysis of cotyledonary nutrient transporter and angiogenic factor gene expression will provide crucial insight into another determinant of placental nutrient transfer capacity. These findings demonstrate that pregnant beef females in a negative nutrient balance will attempt to spare fetal growth but at a certain threshold placental adaptation can be compromised, resulting in intrauterine growth restriction. A better understanding of nutrient delivery to the gravid uterus will allow for improved management strategies to ensure optimal fetal growth. [ABSTRACT FROM AUTHOR]

Nutrient requirements increase dramatically in the late gestation beef female to allow for proper growth and function of the uteroplacenta, fetus, and mammary gland. In fall- and spring-calving systems, late gestation grazing beef cattle often have limited forage nutrient availability. Late gestational nutrient restriction research generally associates decreased prenatal nutrient delivery with programming fetal growth and development, resulting in poor postnatal outcomes. However, the effects gestational nutrient partitioning may have on programming the mammary gland to decrease postnatal nutrient delivery is far less understood. In a fall-calving experiment, primiparous females were individually fed either 100% or 70% of energy and protein requirements from d 160 of gestation until parturition. Nutrient restricted females lost body weight and condition and had less nutrients in maternal circulation during late pregnancy. Calf birth weight was not affected, but nutrient restricted dams had less vigorous calves and 40% less colostrum yield. Colostrum of nutrient restricted females was more concentrated with IgG, and calf 48-h serum IgG indicated that offspring of both treatments had successful passive transfer of immunity. Colostrum of nutrient restricted females had less total lactose, but similar total protein and triglycerides compared with control females. Even when females were fed to meet their energy and protein requirements during lactation, late gestational nutrient restriction reduced milk yield by 15% and decreased milk protein concentration during the first 150 d of lactation. Reduced milk production was partially explained by a 19% reduction in blood flow supplying the mammary gland during this time. Less total lactose, protein, and triglycerides provided by the milk resulted in calf body weight diverging by 42 d of age, and calves born to nutrient restricted dams were 13% smaller at weaning. Interestingly, calf metabolic status pre-weaning was not as severely altered as expected considering milk nutrient and calf growth differences. By d 21 of lactation, metabolic status of previously nutrient restricted dams had returned to concentrations similar to control dams. During lactation, previously nutrient restricted females gained maternal weight faster and increased body condition, but had still not fully recovered to that of control females by weaning. Females were managed together and followed through their second parity to examine effects during the subsequent parity. Previously nutrient restricted dams still weighed less, were in thinner body condition, and had less mammary blood flow during their second lactation. Lactational performance and second parity calf growth were similar between treatments. While late gestational nutrient restriction may not always reduce fetal growth, our results illustrate that impaired postnatal nutrient delivery mechanisms in the cow and calf deserve continued consideration. Additionally, persisting effects in the second parity on maternal size, fleshing ability, and mammary blood flow demonstrate the possibility of long-term programming effects on the dam. [ABSTRACT FROM AUTHOR]

Fall-calving Hereford-SimAngus heifers [single-sired; BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] bred to a single sire were individually fed 100% (control; CON; n = 12) or 70% (nutrient restricted; NR; n = 13) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from day 160 of gestation to calving. Post-calving, all females were fed chopped tall-fescue hay supplemented to meet lactational nutrient requirements in Calan gates to constrain diets of calves to milk only until day 147, then pen-fed in drylots until weaning at day 242 ± 3 (SD). Post-weaning, calves were fed a tall fescue hay-based backgrounding diet in the same large drylots for 53 ± 12 d, then moved to partially covered pens with GrowSafe feeding systems in 2 groups and fed a corn-based feedlot diet (formulated to be 18.3% CP, 1.21 Mcal NEg/kg, DM basis; 89% DM) for 255 ± 3 d (similar days on feed rather than carcass endpoint). Cattle were harvested in a commercial plant, and camera carcass grading was performed. Data were analyzed with maternal treatment, calving date, and calf sex (when P < 0.25) as fixed effects; feedlot group was included for feedlot and carcass measures. We previously reported that birth weight was not affected (P = 0.72), but NR decreased (P < 0.04) milk production by 15%. Calves born to NR dams had reduced ADG from birth to day 147 (P = 0.02), day 147 to weaning (P = 0.08), and birth to weaning (P = 0.003), resulting in NR calves having 13% lighter (P = 0.004) weaning weight. Backgrounding ADG was not affected (P = 0.80) by maternal treatment; thus, feedlot entry BW was 11% less (P = 0.009) in NR calves. On day 28, 56, 84, and 112 on feed, NR calves weighed less (P ≤ 0.09) than control. Final BW was not affected (P = 0.91) by maternal treatment. Feedlot ADG was greater for NR calves from day 168 to slaughter (P = 0.02) and the overall feeding period (P = 0.03), but not before day 168 on feed (P ≥ 0.22). Calves born to NR dams had less (P = 0.02) dressing percentage, but improved (P = 0.02) yield grade and backfat thickness. Hot carcass weight, ribeye area, marbling score, and KPH were not affected (P ≥ 0.26) by maternal treatment. Percent prime, yield grade ≤ 2, and yield grade ≥ 4 were not affected (P ≥ 0.29) by maternal treatment. Overall, late gestational nutrient restriction decreased growth preweaning but increased late finishing growth, without affecting backgrounding or early feedlot growth. These cattle had leaner carcasses after similar days on feed, suggesting that late gestational nutrient restriction altered growth patterns or body composition. [ABSTRACT FROM AUTHOR]

To determine the effects of late gestational nutrient restriction on expelled cotyledonary mRNA expression, fall-calving Hereford × Simmental-Angus heifers [single-sired; BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] bred to a single sire were allocated by fetal sex and expected calving date to receive either 100% (control; CON; n = 12) or 70% (nutrient restricted; NR; n = 11) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth. Beginning on d 160 of gestation, heifers were individually fed chopped sorghum sudan hay (1.74 Mcal ME/kg, 6.69% CP, 72.0% NDF; DM basis) and based on individual intakes, supplemented to meet targeted nutritional planes. Calving was observed for all females and placentas were collected at natural expulsion. Immediately after collection (average: 4.5 h post-calving; range: 2.3 to 12.1 h post-calving), 2 representative cotyledons on the ipsilateral side were cleaned with phosphate buffered saline, and cotyledonary tissue was flash frozen. Total RNA was extracted, and RT-qPCR was performed for mRNA expression of glucose transporters (SLC2A1, SLC2A3, SLC2A4), a fructose transporter (SLC2A5), amino acid transporters (SLC1A1, SLC3A2, SLC7A1, SLC7A5, SLC7A8, SLC38A2), angiogenic factors/receptors (VEGFA, NOS3, FLT1, KDR, GUCY1B3), and pregnancy-associated glycoprotein 2 (PAG2). Relative mRNA expression was analyzed with nutritional plane, treatment initiation date, time to cotyledon sampling, and calf sex (when P < 0.25) as fixed effects. We have previously reported that total uterine blood flow during late gestation was not affected (P = 0.20) by nutritional plane or the nutritional plane × day of gestation interaction. Post-calving, NR dams were 64 kg BW less (P < 0.001) and 2.0 BCS less (P < 0.001), but calf birth weight was not affected (P = 0.72) by nutritional plane. Contralateral placental dry weight tended to be less (P = 0.07) in NR dams, but total placental weight was not affected (P = 0.86) by late gestational nutritional plane. Cotyledonary relative mRNA expression of SLC2A3 and SLC38A2 was greater (P = 0.05) and relative expression of SLC2A1, SLC2A4, and NOS3 tended to be greater (P = 0.07) in NR dams compared with CON. Late gestational nutritional plane did not affect (P = 0.13) cotyledonary relative mRNA expression of FLT1, GUCY1B3, KDR, PAG2, SLC1A1, SLC2A5, SLC3A2, SLC7A1, SLC7A5, SLC7A8, and VEGFA. In summary, first parity beef females who experienced late gestational nutrient restriction maintained uterine blood flow and placental mass and had 4 nutrient transporters and 1 angiogenic factor upregulated in cotyledons, all which likely contributed to their conservation of fetal growth. [ABSTRACT FROM AUTHOR]

We hypothesized that maternal circulating AA concentrations would be reduced by late gestational nutrient restriction, indicating less available nutrients for transport by the uteroplacenta to the growing fetus. Fall-calving Hereford-SimAngus heifers [single-sired; BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] bred to a single sire were allocated by fetal sex and expected calving date to receive either 100% (control; CON; n = 12) or 70% (NR; n = 13) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from day 160 of gestation to calving. Heifers were individually fed chopped sorghum sudan hay (1.74 Mcal ME, 6.66% CP, 72.0% NDF; DM basis) and based on individual intakes, supplemented to meet targeted nutritional planes. Jugular blood samples were obtained on days 159 (Pre-treatment), 202, and 244 of gestation, and 1 h post-calving to determine serum concentrations of the 20 common AA (except cysteine), 1-methyl histidine, and 3-methyl histidine. Gestational and post-calving AA were analyzed separately with nutritional plane, treatment initiation date, and calf sex (when P < 0.25) as fixed effects. Gestational AA included day and nutritional plane x day using repeated measures. We have previously reported that dam BCS was less (P ≤ 0.04) by day 202 of gestation and dam BW was less (P ≤ 0.01) by day 223 of gestation for NR dams. Post-calving, NR dams were 64 kg BW and 2.0 BCS lless (P < 0.001), but calf birth weight was not affected (P = 0.72) by nutritional plane. Histidine, lysine, and methionine were greater (P ≤ 0.03) in NR dams on day 202 of gestation. Tryptophan and valine were less (P ≤ 0.05) while methionine and total AA tended to be less (P ≤ 0.08) on day 244 of gestation in NR dams. Aspartic acid, glutamic acid, and tyrosine were less (P ≤ 0.03), but 3-methyl histidine was greater (P ≤ 0.01) on days 202 and 244 of gestation in NR dams. 1-methyl histidine was greater (P ≤ 0.05) at all 3 gestational timepoints but leucine was less (P = 0.03) in NR dams during gestation. Post-calving, glutamic acid, leucine, and valine were less (P ≤ 0.04), and methionine, threonine, tryptophan, tyrosine, and total AA tended to be less (P ≤ 0.10) in NR dams. Histidine, 1-methyl histidine, 3-methyl histidine, and serine were greater (P ≤ 0.03) in NR dams post-calving. In summary, late gestational nutrient restriction reduced total maternal circulating AA and altered the maternal serum AA profile, but calf birth weight was not affected. Individual AA that were greater or unaffected in NR dams were likely indicative of body protein catabolism occurring to meet nutrient requirements. [ABSTRACT FROM AUTHOR]

Sixty nonpregnant, nulliparous Rambouillet ewes (51 ± 1.4 kg initial body weight) were used in a completely randomized design to determine 1) if rumen-protected l-Arg (RP-ARG) supplementation would increase serum concentrations of amino acids resulting from Arg supplementation and metabolism, and decrease serum concentrations of amino acids that compete with Arg for transporters, 2) if RP-ARG supplementation would alter carotid artery hemodynamics, and 3) the most effective oral dose of RP-ARG to positively increase both circulating amino acids and improve peripheral tissue blood perfusion as measured by carotid hemodynamics. Ewes were penned individually in a temperature-controlled facility. Ewes were randomly assigned to one of four treatments: a control group that received no supplemental Arg (CON ; 50 g of finely ground corn, only), or Arg-supplemented groups that received 90 (90), 180 (180), or 360 (360) mg RP-ARG·kg BW−1·d−1 mixed in 50 g of finely ground corn. Supplements were administered once daily for 14 d and fully consumed before the delivery of a total pelleted diet at 0630 and 1830 hours daily. Baseline and final blood samples were collected at days 0 (before treatment initiation) and 15, respectively. Doppler ultrasound was used to assess carotid arterial hemodynamics at 0600 hours on days 0 (before treatment initiation), 5, 8, 12, and 15. After 14 d of supplementation, ewes fed 180 had greater Arg (P = 0.05) and Orn (P = 0.05) and tended (P = 0.08) to have greater Asp in serum than ewes fed 90, and for these amino acids, ewes fed 180 were similar (P ≥ 0.16) compared with ewes fed 360. All supplemented ewes (90, 180, and 360) had a negative change (P = 0.02) from baseline when normalized to CON for the pulsatility and resistance indices, which indicate greater distal tissue blood perfusion and lower vascular resistance of blood flow, respectively. Additionally, there were quadratic responses for the pulsatility and resistance indices (P = 0.03 and 0.01, respectively) where ewes fed 180 had the greatest change from baseline when normalized to CON. Results indicate that Arg supplementation increased serum amino acid concentrations and improved peripheral tissue blood perfusion. The 180 mg·kg BW−1·d−1 RP-ARG dose was determined to be the optimal dose for nonpregnant, nulliparous Rambouillet ewes. [ABSTRACT FROM AUTHOR]

Changes in locomotor activity of beef females during the 72 h prepartum were determined in 3 experiments: (i) a 2-yr study with spring-calving multiparous cows (Exp. 1; n = 34 and 27 for years 1 and 2, respectively); (ii) spring-calving primiparous (first pregnancy; n = 13) and multiparous (n = 21) dams (Exp. 2); and (iii) fall-calving multiparous cows (Exp. 3; n = 33). For all experiments, IceQube activity monitors (iceRobotics, Edinburgh, UK) were placed above the left hind fetlock of pregnant females ≥3 d prepartum. During the calving season, females were housed in 18 × 61 m drylots with ad libitum access to hay or haylage. Parturition was closely monitored, and time of birth was noted. Motion index, standing and lying time, step count, and the number of lying bouts for each dam (summed per hour) were determined for the 72 h preceding calving. Within experiment, data were analyzed by day (days −3 to −1 prepartum), by 6-h period during the final 24 h prepartum, and by hour during the final 6 h prepartum using a mixed model with time as a repeated effect. Year was also included as a fixed effect in Exp. 1. Fixed effects of parity and time prepartum × parity were included for Exp. 2. In all 3 experiments, motion index, standing time, step count, and the number of lying bouts were greater (P < 0.001) on day −1 compared with days −2 and −3 prepartum. In the 24 h prepartum, dams had greater (P < 0.01) motion index, standing time, step count, and the number of lying bouts during 6 h preceding parturition compared with −11 to −6 h in all experiments. Motion index, step count, and lying bouts changed (P ≤ 0.02) during the last 6 h in all experiments. Primiparous dams had more (P ≤ 0.01) lying bouts than multiparous dams during the last day and −11 to −6 prepartum. In all experiments, the number of lying bouts more than doubled (P < 0.001) from −2 to −1 prepartum, with no effect of year (P = 0.57) in Exp. 1 or parity (P ≥ 0.29) in Exp. 2. This suggests that lying bout changes may be the most reliable of parameters measured in detection of calving. Moreover, fall-calving cow behavioral patterns were similar to changes observed in spring-calving females, suggesting that calving season may have minimal effects on pre-calving behavior. Overall, electronic locomotor activity monitors can detect behavioral changes peripartum in beef heifers and cows. More research is necessary to determine if these can be used to remotely sense early signs of parturition in beef cattle. [ABSTRACT FROM AUTHOR]

Our objective was to determine the effects of dry and wet conditions during the preweaning on subsequent feedlot performance and carcass characteristics of beef cattle. Steers (n = 7,432) and heifers (n = 2,361) finished in 16 feedlots in southwestern Iowa through the Tri-County Steer Carcass Futurity Cooperative were used for a retrospective analysis. Cattle originated in the Midwest (Iowa, Missouri, Indiana, Illinois, and Minnesota) and were born in February, March, or April of 2002 through 2013. Feedlot performance and carcass composition data were obtained for each animal. Palmer Drought Severity Index (PDSI) values were obtained for each animal's preweaning environment on a monthly basis. Mean PDSI values were used to classify conditions as dry (≤−2.0), normal (>−2.0 and <2.0), or wet (≥2.0) for the cool (April and May), warm (June through August), and combined (April through August) forage growing seasons preweaning. Mixed models were used to evaluate the effects of PDSI class on subsequent performance. Calf sex, date of birth (as day of year), year, and feedlot were also included as fixed effects. When considering PDSI class during the cool season, cattle from normal and wet classes had a greater feedlot delivery BW (P < 0.0001) than dry. Dry and normal classes had greater (P ≤ 0.02) delivery BW than wet during the warm and combined seasons, however. For the cool season, average daily gain was greater (P < 0.0001) for the dry class than normal and wet. Cattle from the normal class for the cool season had greater (P = 0.001) final BW than wet, but the wet class had the greatest (P < 0.04) and dry class had the lowest (P < 0.01) final BW during the warm season. During the cool season, HCW was greater (P < 0.007) for the normal than wet class, although HCW was greater (P ≤ 0.02) for wet compared with dry and normal during the warm season. Calculated yield grade was lower (P ≤ 0.006) for the normal class during the cool season compared with dry and wet. For both the warm and combined seasons, the dry class had lower (P ≤ 0.004) calculated yield grade compared with normal and wet. Carcasses from cattle that experienced normal or wet warm seasons had greater (P ≤ 0.0005) marbling scores than dry, and normal had greater (P = 0.0009) marbling score than dry for the combined seasons. In conclusion, these data indicate that both dry and wet conditions during the preweaning phase may impact ultimate feedlot performance and carcass composition. [ABSTRACT FROM AUTHOR]

We hypothesized that cows grazing stockpiled tall fescue (STF) during late gestation would have increased nutrient intake, resulting in improved metabolic status and fetal growth compared with cows consuming summer-baled tall fescue hay. Multiparous, spring-calving, crossbred beef cows (year 1: n = 48, year 2: n = 56) were allocated by body weight (BW), body condition score (BCS), age, service sire, and expected calving date to 1 of 2 forage systems (4 rep/system) in mid-November on day 188 of gestation: strip-graze endophyte- infected STF in 4.05 ha pastures or consume ad libitum endophyte-infected summer-baled tall fescue-based hay in uncovered dry lots. Treatments were terminated 1 wk postpartum, and cow-calf pairs were managed together until weaning. Data were analyzed with forage system, year, and their interaction as fixed effects. Sampling day was a repeated effect for cow metabolites and hormones. Calf date of birth was in the model when P < 0.25; pasture or pen was the experimental unit. Cow prepartum BW was not affected (P . 0.424) by forage system, but cows grazing STF tended (P = 0.09) to have greater BCS at day 35 and had greater (P = 0.03) final precalving BCS than hay-fed cows. Additionally, final precalving 12th rib fat thickness tended (P = 0.09) to be greater for STF than hay-fed cows. Calves born to cows fed hay only weighed 10.2% less (P = 0.03) at birth than calves born to cows consuming STF, indicating reduced fetal growth. Postpartum cow BW, BCS, first service conception rate, and overall pregnancy rate were not affected (P . 0.15) by late gestational forage system. After day 0, serum urea N was greater (P < 0.001) in cows consuming STF on all days measured. Cows grazing STF also tended (P = 0.08) to have greater plasma glucose than cows consuming hay. Serum nonesterified fatty acids (NEFA) were greater (P < 0.001) in cows grazing STF on day 56 in year 1 and on day 77 and 99 in year 2. Serum triiodothyronine was less (P = 0.03) on day 0, but greater (P = 0.004) on day 99, in cows grazing STF. Cows grazing STF tended (P = 0.06) to have greater thyroxine on day 77 in year 1. Serum cortisol was greater (P = 0.003) on day 35 and tended (P = 0.10) to be greater on day 99 in cows grazing STF. Calf birth weight was positively correlated with prepartum maternal serum urea N (r = 0.31, P = 0.002) and NEFA (r = 0.12, P = 0.005). In this study, cows grazing STF had increased nutrient intake during late gestation, resulting in greater fetal growth. [ABSTRACT FROM AUTHOR]

Our objectives were to determine changes in colostrum yield and composition across the 36 hours post-calving and effects of late gestational nutrient restriction (NR) on these changes. Fall-calving, crossbred beef heifers (BW: 472 ± 33 [SD] kg; BCS: 5.4 ± 0.5) were individually fed 100% (control; CON; n = 13) or 70% (NR; n = 13) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, growth, and pregnancy from d 160 of gestation to parturition. Calves were removed from dams immediately post-calving and pre-suckling. Colostrum was handmilked from all quarters at 1, 12, 24, and 36 h to determine total colostrum volume and weight. Colostrum protein, triglycerides, and milk urea nitrogen (MUN) concentration were analyzed using colorimetric assays on a UV-visible light microplate reader. Data were analyzed using fixed effects of treatment, hour, treatment × hour (repeated measures); calf sex, maternal sire, and treatment initiation date were covariates. Colostrum yield was affected (P < 0.02) by the treatment × hour interaction. Colostrum volume and weight were 28% less (P = 0.03) for NR than CON at 1 h. For both treatments, colostrum volume and weight decreased (P = 0.04) from 1 to 12 h, before increasing (P = 0.02) from 12 to 36 h. Triglyceride concentration was greater (P = 0.03) in NR than CON. Both triglyceride concentration and total protein decreased (P = 0.01) from 1 to 24 h. Protein concentration decreased (P < 0.001) from 1 to 36 h. Total triglycerides and MUN decreased (P < 0.001) from 1 to 12 h, before total MUN increased (P < 0.001) from 12 to 36 h and total triglycerides increased (P = 0.004) from 24 to 36 h. In conclusion, nutrient restriction may only affect colostrum yield at 1 h, and colostrum nutrient content decreases dramatically after the first milking. [ABSTRACT FROM AUTHOR]

We hypothesized that late gestational nutrient restriction (NR) would decrease organ mass in neonatal calves. Fall-calving crossbred beef heifers (BW: 466 ± 30 [SD] kg; BCS: 5.4 ± 0.5) bred to a single sire were individually fed 100% (control; n = 10) or 70% (nutrient restricted; NR; n = 12) of NASEM metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from d 160 of gestation to calving. Diets were based on chopped sorghum sudan hay and supplemented to meet targeted nutritional planes. Calves were removed immediately post-calving and fed colostrum and milk replacer relative to BW until euthanasia (48.7 ± 0.4 h of age) for organ mass determination. Nutritional plane was a fixed effect, and maternal sire, calf sex (when P < 0.25), and date of study initiation were covariates. Post-calving, NR dams were 62 kg BW and 2.1 BCS less (P < 0.001) than controls. Calf BW, liver, large intestine, omental/mesenteric fat, kidney, and heart weights were less (P = 0.05) and carcass, rumen/reticulum/omasum, stomach complex, and total gastrointestinal tract weights tended to be less (P = 0.09) in offspring from NR dams. Maternal nutrient restriction did not affect (P = 0.11) weights of the small intestine, pancreas, abomasum, spleen, perirenal fat, adrenals, lungs, femur, and brain. Expressed per BW, lung weight was greater (P = 0.05), and brain and femur weight tended to be greater (P = 0.10) in calves from NR dams, but other organ masses were unaffected (P = 0.15). Expressed relative to brain weight, liver and large intestine weights were less (P = 0.04) and carcass, total gastrointestinal tract, omental/mesenteric fat, and kidney weights tended to be less (P = 0.08) in NR. In summary, late gestational NR decreased some organ masses in neonatal calves while sparing other tissues via asymmetric growth. [ABSTRACT FROM AUTHOR]

The Morrill Land Grant Act of 1862 created colleges to "benefit the agricultural and mechanical arts" and established one college per state "where the leading object shall be... to teach such branches of learning as are related to agriculture... to promote liberal and practical education". Further, the purpose of Smith-Lever Act of 1914 is "to aid in diffusing among the people of the United States useful and practical information on subjects relating to agriculture...and to encourage the application of the same". From this legislation the role of universities was established to research and disseminate scientific information to various audiences. A key component of these legislative charges is the feedback loop between university faculty, producers, and industry professionals to assure the continuance of "liberal and practical education". This feedback loop ensures that relevant information is pursued by faculty and provides an avenue for producer needs to be communicated back to faculty. Development of personal relationships between stakeholders and faculty is an integral part of the information flow. On-farm research and in-person educational programs, along with on-the-ground visits by faculty, have historically served an important mechanism for information flow and feedback. However, across the U.S., Animal Science undergraduate enrollment has increased dramatically while faculty and field staff extension FTEs have declined. Funding for such has remained stable over the past 20 years. These trends resulted in prioritization for undergraduate teaching and grantsmanship among faculty. The advent of electronic communications has diminished personal face-to-face interactions and on-site visits by faculty to production entities. Consulting with producers at their business often is most rewarding in learning and respected by producers, however this interaction is sometimes viewed as "service" which is viewed as a low priority by some administrators. This symposium will examine best practices by faculty to ensure land-grant universities align with the legislative mandates established by Congress and benefit from valuable interaction with clientele. [ABSTRACT FROM AUTHOR]

Fall-calving Herford-SimAngus heifers were individually fed either 100% (control; CON, n = 10) or 70% (nutrient restricted; NR, n = 12) of NASEM metabolizable energy and metabolizable protein requirements from d 160 of gestation to calving. Postpartum cows were individually fed 100% of energy and protein requirements until d 149 of lactation, then fed tall fescue hay or pasture as a single group through parity 2. Second parity cow performance and calf size were measured at birth, d 30, and d 60 post-calving. Singlequarter colostrum yield was collected pre-suckling. At d 30 and 60 of lactation, 4-hour milk yield was collected. Data were analyzed with the fixed effect of first parity nutritional plane, and calving or breeding date, calf sex, and calf sire (calf measures) were covariates. Milk yield included day and day x treatment (repeated measures). We previously reported that in parity 1, NR reduced (P = 0.04) colostrum and milk yield, calf weaning weight, and dam weaning BCS. From calving to d 60 of parity 2, CON cows had greater (P = 0.008) BCS and greater (P = 0.003) backfat on d 30. Additionally, CON cows had greater (P = 0.002) BW compared with NR at d 30 and 60 of lactation. Calf size was not affected (P = 0.17) by first parity nutritional plane except that cannon length at birth and d 60 tended (P = 0.08) to be longer in CON calves. Colostrum and milk volume and weight were not affected (P = 0.37) by first parity nutritional plane. Milk yield was greater (P = 0.001) at d 30 than d 60. These data indicate that cow BW and energy reserves remained less in parity 2 when heifers experienced late gestational nutrient restriction, but calf size, colostrum yield, and milk yield were unaffected in the second parity. [ABSTRACT FROM AUTHOR]

Fall-calving Hereford-SimAngus heifers (single-sired; BW: 451 ± 28 [SD] kg; BCS: 5.4 ± 0.7) bred to a single sire were individually-fed 100% (control; CON; n = 12) or 70% (nutrient restricted; NR; n = 13) of NASEM net energy and metabolizable protein requirements for maintenance, pregnancy, and growth from d 160 of gestation to calving. Post-calving, all females were limit-fed chopped tall-fescue hay supplemented to meet lactational nutrient requirements in Calan gates to constrain calves' diets to milk only until d 147. Four-hour milk yields were measured 5 times; calf size was determined every 21 d. Data were analyzed with treatment, calving date, and calf sex (when P < 0.25) as fixed effects; day and day x treatment were included for milk yield. From calving to d 147, CON cows had greater (P ≤ 0.003) BW, BCS, and backfat, but NR cows gained more (P ≤ 0.004) BW, BCS, and backfat. Milk weight and volume was 15% less (main effect; P < 0.04) for NR cows. Calf size did not differ at birth (P ≥ 0.27). From d 42 to 147, calves born to NR dams had lower (P ≤ 0.02) BW. Heart, abdominal, and flank girths were less (P ≤ 0.07) for NR calves through d 147. Calf ribeye area tended to be less (P ≤ 0.11) in NR calves at d 42, 84, and 126. Nutrient restricted calves had less shoulder to rump length (d 63 to 147; P ≤ 0.08), shoulder height (d 63 to 126; P ≤ 0.02), cannon length (d 42 to 105 and 147; P ≤ 0.09), and cannon circumference (d 63 and 105 to 147; P ≤ 0.06). These data indicate that even when dams are fed to meet lactational requirements, milk yield and calf growth are reduced by late gestational nutrient restriction. [ABSTRACT FROM AUTHOR]

To determine effects of late gestational nutrient restriction (NR) on neonatal blood chemistry and hematology, primiparous fall-calving crossbred beef heifers [BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] were individually fed either 100% (control; CON; n = 12) or 70% (n = 13) of NASEM net energy and metabolizable protein requirements for maintenance, pregnancy, and growth from d 160 of gestation to parturition. Calf jugular blood was obtained at 0 (pre-suckling), 6, 12, 24, and 48 h postnatally to determine serum chemistry and complete blood cell count. Data were analyzed with fixed effects of treatment, hour, and their interaction, using repeated measures. Calving date was a fixed effect; calf sex was included when P < 0.25. The treatment x hour interaction (P < 0.10) affected total protein, globulin, gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), creatinine, creatine kinase, red blood cells (RBC), hemoglobin, hematocrit, sodium, anion gap, and potassium. Total protein and globulin at 6 to 48 h were greater (P = 0.02) in NR calves. Calves from NR heifers had greater (P < 0.08) GGT at 6, 12, and 48 h and greater (P = 0.07) AST at 0 to 24 h. Creatinine at 24 h and creatine kinase at 6 to 24 h were greater (P < 0.04) in NR calves. Hematocrit from 6 to 24 h and RBC and hemoglobin at 6 and 12 h were greater (P = 0.09) in CON calves. Sodium from 0 to 48 h and anion gap at 6 h were greater (P < 0.09) in CON calves. Calves from NR heifers had greater (P = 0.03) 0 h potassium. Treatment affected chloride, which was greater (P = 0.08) in CON calves. These data indicate calves born to nutrient restricted heifers may experience more trauma at calving but have improved passive transfer. [ABSTRACT FROM AUTHOR]

To determine the effects of late gestational nutrient restriction (NR) on heifer performance, fetal growth, and calving difficulty, single-sired fall-calving Hereford-SimAngus heifers (BW: 451 ± 28 [SD] kg; BCS: 5.4 ± 0.7) bred to a single sire were allocated by fetal sex and expected calving date to either 100% (control; CON; n = 12) or 70% (n = 13) of NASEM net energy and metabolizable protein requirements for maintenance, pregnancy, and growth. Beginning on d 160 of gestation, heifers were individually fed chopped sorghum sudan hay (1.74 Mcal ME, 6.66% CP, 72.0% NDF; DM basis) and based on individual intakes, supplemented to meet targeted nutritional planes. Dam BW, BCS, and backfat (BF) were determined pre-treatment, every 21 d (BW) or 42 d (BCS and BF) during treatments, and postcalving. At birth, calf BW and size (length, heart girth, abdominal girth, flank girth, cannon circumference, cannon length, shoulder height, and ribeye area) were measured. Data were analyzed with treatment, treatment initiation date, and calf sex (when P < 0.25) as fixed effects. Dam BW tended to be less (P = 0.09) and BCS was less (P = 0.04) at d 202 of gestation for NR dams. Dam BW, BCS, and BF were less (P ≤ 0.01) in NR dams for the remainder of gestation. Post-calving, NR dams weighed 64 kg less (P ≤ 0.01) than CON, with a BCS of 3.6 ± 0.1. Nutrient restriction did not affect (P ≥ 0.27) calf gestation length, BW, or size. Calf BW as % post-calving dam BW tended to be greater (P = 0.09) for NR calves. Fetal presentation was normal for all CON births, while 23.1% of NR dams had fetal malpresentation (P = 0.12). In the current study, NR dam BW and BCS were sacrificed during late gestation without altering fetal growth trajectory. [ABSTRACT FROM AUTHOR]

To determine effects of late gestational maternal nutrient restriction (NR) on uteroplacental blood flow and placental growth, primiparous fall-calving crossbred beef heifers [BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] were individually-fed either 100% (control; CON; n = 12) or 70% (n = 13) of energy and protein requirements for maintenance, pregnancy, and growth during the last 120 days of gestation. Transrectal color Doppler ultrasonography of both uterine arteries was conducted pretreatment and every 21 d during treatments. Placentas were split into ipsilateral and contralateral sides, dissected (cotyledonary vs. intercotyledonary), and dried. Data were analyzed with treatment, treatment initiation date, and calf sex (when P < 0.25) as fixed effects. Uterine blood flow included day and treatment x day (repeated measures). Dam BW was less (P ≤ 0.01) from d 223 of gestation through parturition for NR dams, but calf BW was not affected (P = 0.72) by treatment. The interaction affected (P < 0.01) heart rate, where NR dams had decreased heart rate after treatments began. Treatment did not affect (P ≥ 0.20) uterine artery blood flow or hemodynamics, but all variables were affected (P ≤ 0.04) by day. Contralateral total and cotyledonary weights tended (P ≤ 0.09) to be greater and ipsilateral and total cotyledonary:intercotyledonary ratios were greater (P ≤ 0.01) for CON. Cotyledon number, cotyledon size, and total cotyledonary, intercotyledonary, and placental weight were not affected (P ≥ 0.15) by treatment. Relative to dam BW, uterine blood flow was not affected (P = 0.83), but relative placental weight tended to be greater (P = 0.09) in NR dams. In the current study, NR dams lost maternal BW during late gestation and had less contralateral placental growth, yet uterine blood flow was maintained and placental size relative to BW ensured fetal growth similar to CON offspring. [ABSTRACT FROM AUTHOR]

We hypothesized that late gestational nutrient restriction (NR) would reduce colostrum yield and impair offspring transition to postnatal life. Primiparous, fall-calving crossbred beef heifers (BW: 451 ± 28 [SD] kg; BCS: 5.4 ± 0.7) were individually-fed either 100% (control; CON; n = 12) or 70% (n = 13) of NASEM net energy and metabolizable protein requirements for maintenance, pregnancy, and growth from d 160 of gestation to parturition. Delivery duration was determined as minutes from first fetal feet expulsion to birth. Calves were reared naturally by their dams and monitored for times from birth to first sternal recumbency, attempt to stand, and stand; vigor scores (1 = very weak, 5 = extremely vigorous) were assigned at 2, 5, 10, and 20 min of age. Total colostrum from one rear quarter was collected pre-suckling. Calf rectal temperatures were recorded at 0, 6, 12, 24, and 48 h postnatally. Data were analyzed with the fixed effects of treatment (single point) or treatment, hour, and their interaction (over time, using repeated measures). Date of calving was a fixed effect; calf sex was included when P < 0.25. Heifers fed CON had greater (P = 0.04) colostrum weight and volume than NR. Although gestational nutrition did not affect (P = 0.72) calf birth weight, calves born to CON heifers had faster (P = 0.02) times to stand and tended to have faster (P = 0.09) times to attempt to stand. Calves from CON heifers had greater (P = 0.05) 20 min vigor scores. Rectal temperatures at 0 h were greater (P = 0.02) in CON calves, but at 24 h were greater (P = 0.04) in NR calves. These data indicate that heifers nutrient restricted during late gestation have reduced colostrum yield and less vigorous calves, which may influence postnatal calf survival. [ABSTRACT FROM AUTHOR]

To determine the effect of season on perinatal nutrient availability, assessed through fetal growth, calf vigor, and neonatal circulating metabolites, multiparous and primiparous dams (age: 4.7 ± 2.4 yr; BCS: 5.3 ± 0.6) from 4 spring (2014-2017; n = 202) and 4 fall (2015, 2017-2019; n = 177) calving experiments were observed during parturition. Time to stand (spring: 67; fall: 104) was determined as minutes from birth to standing for 5 sec. After birth, calf BW and size (spring: 99; fall: 169; length, heart girth, abdominal girth, and cannon circumference) were recorded. Jugular blood samples were obtained from 63 spring and 89 fall calves at 0 (pre-suckling), 6, 12, 24, and 48 h postnatally. Data were analyzed either with the fixed effect of season (single point) or the fixed effects of season, hour, and their interaction with hour as a repeated effect (over time); calf sex was included when P < 0.25. Experiment was a random effect. Fall-born calves tended to have lighter (P = 0.09) BW and faster (P = 0.05) time to stand than spring-born calves. Season did not affect (P ≥ 0.18) other calf size measures. The season x hour interaction (P ≤ 0.07) affected circulating glucose, nonesterified fatty acids (NEFA), triglycerides, urea nitrogen, globulin, and total protein. Spring-born calves had greater (P ≤ 0.009) 0 h glucose, 0 and 6 h NEFA, and 0, 6, 12, and 48 h triglycerides than fall-born calves. Fall-born calves had greater (P = 0.03) total protein at 24 h and tended to have greater (P ≤ 0.10) total protein and urea nitrogen at 48 h and globulin at 24 h. Season affected albumin, which was greater (P = 0.003) in fallborn calves. These data suggest that calving season influences perinatal nutrient availability, which may impact the transition to postnatal life. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to evaluate relationships of dam parity and calf suckling within 4 h postnatal with neonatal circulating metabolite concentrations, neonatal environment, and postnatal growth. For the experiment, 36 Angus, Hereford, and crossbred dams (age = 4.0 ± 1.74; multiparous (n = 5) and primiparous (n = 31); BCS = 6.5 ± 1.04; average calving date = April 4, 2018) were used. Calves were observed using a digital video recording system for 4 h after birth to determine suckling success [S = suckled (n = 27) or NS = did not suckle (n = 5) ≤ 4 h]. Jugular blood samples were obtained from calves at 24 (24.4 ± 1.73) and 48 to 72 (54.7 ± 9.08) h of age to determine serum blood urea nitrogen (BUN), glucose, non-esterified fatty acids (NEFA), and total protein (TP). Postnatal growth measures were collected at 50.4 ± 13.6 d and 162 ± 19.7 d of age. Calf BW was greater (P ≤ 0.02) at 50 and 162 d of age and ADG (0 to 162 d) was greater (P = 0.04) for S than NS calves, however birth BW was not different (P = 0.69). Ambient temperature at parturition was colder (P = 0.03) for NS calves than S calves. Serum glucose at 24 and 72 h was greater (P ≤ 0.03) in S calves than NS calves, however NEFA, BUN, and TP were not affected (P ≥ 0.09) by suckling success at either sampling time. Dam parity had no effect (P ≥ 0.12) on calf circulating metabolites at 24 and 72 h postnatal. In conclusion, the success of beef calves to suckle within 4 h of birth is associated with greater circulating glucose, warmer ambient temperature at birth, and greater postnatal BW and ADG. [ABSTRACT FROM AUTHOR]

Mineral nutrition during pregnancy has long been known to impact fetal growth and development. This is evidenced by a multitude of mineral deficiency-related causes for embryonic loss, abortion, stillbirth, or neonatal death, including poor or inappropriate fetal development that can be either reversible or irreversible postnatally. Both macro and trace mineral needs of the dam are known to increase with the fetal growth of advancing gestation due to greater metabolic stress and demand, as well as tissue development and deposition in the fetus. Fetal deposition of many trace minerals is especially important for neonatal use while consuming milk with low mineral concentrations and facing a multitude of immune challenges. In the last 2 decades, many laboratories have focused on "developmental programming," or the effects of maternal nutrition on fetal and neonatal development and ultimately long-term health and productivity of livestock. Despite this, the role of macro and trace minerals in short-and long-term consequences of developmental programming is still unclear for many minerals and species. Taken together, research in ruminants and swine demonstrate that mineral intake and source during pregnancy can have a large effect on fetal growth and development that lasts into the neonatal and preweaning periods. Some studies suggest that supranutritional mineral intake may have a positive benefit during gestation or neonatal periods. Moreover, some data suggest that mineral requirements may be greater than currently thought to accommodate the rapid fetal growth and preparation for lactation that occurs during late gestation. Continued research is necessary to determine mineral requirements of livestock during pregnancy, especially when considering their longreaching subsequent effects on offspring. Additionally, increased understanding of perinatal transfer of trace minerals can aid in our management of pregnant dams and their offspring. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine whether repeated freeze and thaw cycles alter bovine circulating metabolite concentrations, which serve as indicators of nutrient utilization. In research settings, it is common to thaw and refreeze samples when confirming results or performing further analyses; thus, it is important to determine if these actions alter metabolites. Jugular blood samples were collected from beef cows (n = 14) and fall-born calves (n = 14) at weaning. Samples were processed into multiple aliquots and stored at -20°C until analysis. Samples were thawed at 4°C for 8 to 10 h on each day of analysis and refrozen for at least 48 h between cycles. Concentrations of serum nonesterified fatty acids (NEFA), serum urea N, plasma triglycerides, and plasma glucose were analyzed using commercially available kits on a UV-visible light plate reader. Data were analyzed with sample type (cow vs. calf), thaw (cycles 1-4), and their interaction in a mixed model. Additionally, R2 were determined among freeze-thaw cycles within each metabolite. Thaw cycle impacted glucose concentrations (P = 0.03); other metabolites were unaffected (P > 0.25). Thaw cycle and its interaction with sample type did not affect metabolite concentrations (P > 0.33). Sample type did not affect triglyceride and BUN concentrations (P > 0.34). There was a type effect (P < 0.0001) for NEFA and glucose; NEFA were greater in cows and glucose was greater in calves. There was a strong relationship between urea N thaw cycles 1 and 2 (R2 = 0.88), which was also apparent between all other urea N, triglycerides, NEFA, and glucose cycles (R2 = 0.79, 0.96, 0.91, and 0.61 respectively). These data indicate that repetitive freezing and thawing of bovine serum and plasma samples has little effect on non-esterified fatty acids, triglycerides, and urea N, but may impact glucose concentrations. [ABSTRACT FROM AUTHOR]

Expelled placentas and calf size at birth were collected from crossbred beef cows during Spring 2017 (n = 27; age: 2-7 yr), Fall 2017 (n = 24; age: 3-6 yr), and Fall 2018 (n = 22; age: 2-4 yr) to determine the relationships of placental characteristics with cow parameters, calf sex, and fetal growth. Placentas deemed complete were dissected (cotyledonary vs. intercotyledonary) and dry weights determined. Mixed linear models were used to individually determine main effects of peripartum BCS category (< 5, =5, or =6), cow age category (2, 3-4, or 5-7 yr), and calf sex on placental measures. Study was included in all models. Correlations were determined for placental characteristics with pre-calving cow BW and calf size. Cow BCS and calf sex had no effect (P = 0.25) on placental characteristics. Primiparous cows had less (P = 0.02) total placental and average cotyledon weights compared with young cows. Cow BW and calf BW had moderate positive correlations (P < 0.001) with intercotyledonary and total placental weights and weak positive correlations (P = 0.01) with cotyledonary weight. Cow BW had a weak negative correlation (P = 0.05) with placental efficiency [calf BW/placental weight]. Average cotyledon weight had a moderate positive correlation (P < 0.001) with cow BW and a weak positive correlation (P = 0.001) with calf BW. Shoulder to tailhead length had a weak positive correlation (P = 0.001) with placental efficiency. Heart girth had moderate positive correlations (P < 0.001) and abdominal girth had weak positive correlations (P = 0.04) with cotyledonary, intercotyledonary, total placental, and average cotyledon weights. Ponderal index [calf BW/length3] had a weak positive correlation (P = 0.06) with cotyledonary, intercotyledonary, and total placental weights. These data suggest that fetal and placental growth occur in concert; however, which imparts more influence on the other is unknown. [ABSTRACT FROM AUTHOR]

To determine effects of cow BCS and calving season on calf vigor and size and the relationship of calf size with vigor, 310 multiparous and primiparous beef cows (age: 4.6 ± 2.2 yr; BW: 663 ± 86 kg; BCS: 5.3 ± 0.6) from 3 spring (2015, 2016, 2017) and 4 fall (2015, 2017, 2018, 2019) calving seasons were observed during parturition. Time to stand (n = 191) was determined as minutes from birth to standing successfully for 5 sec. Within 24 h, calf BW (n = 187) and size [shoulder to tailhead length (STL), heart girth (HG), and abdominal girth (AG; n = 154)] were recorded. Data were analyzed using a mixed model containing effects of calving season (spring and fall), BCS category (< 5, =5, =6), and their interaction. Correlations were determined between time to stand and calf measurements separately for spring (n = 79) versus fall (n = 111). Cows with BCS < 5 gave birth to lighter (P = 0.02) calves that tended to have a faster (P = 0.13) time to stand than =5 and =6. Calves from cows with BCS =6 tended to have greater (P = 0.09) STL than =5 and < 5. Calves from cows with BCS < 5 had smaller (P = 0.13) HG than =5. Fall-born calves tended to have smaller (P = 0.06) BW, HG, and AG than springborn calves. Within fall calves, there tended to be a positive relationship (r = 0.16; P = 0.09) between time to stand and calf BW. Despite this, spring calves had a negative relationship (r = -0.26; P = 0.02) between time to stand and calf BW. In conclusion, cow BCS and calving season affect calf size and may affect calf vigor. These data suggest that calving season may dictate the relationship between calf vigor and size. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the relationships of neonatal beef calf behavior with calf serum metabolites. Angus, Hereford and crossbred beef females (n = 36; age = 4.0 ± 1.74; BCS = 6.5 ± 1.04; primiparous =5, multiparous = 31; calving date = April 4, 2018) and their calves were monitored continuously from 0 to 4 h post-parturition using a digital video recording system from March to May 2018. Jugular blood samples were obtained from calves at 24 (24.4 ± 1.73) and 48 to 72 (54.7 ± 9.08) h postnatal to determine serum blood urea nitrogen (BUN), glucose, non-esterified fatty acids (NEFA), and total protein (TP). Video was analyzed for behavior latencies calculated from time of birth to time when calf shakes head, kneels, attempts to stand, stands, and suckles. Time to stand had a weak positive correlation (P = 0.03) with time to suckle. Time to shake head had a moderate positive correlation (P ≤ 0.04) with both time to attempt to stand and time to stand, but did not correlate (P = 0.99) with time to suckle. Dam parity (multiparous or primiparous) did not affect (P ≥ 0.20) calf vigor measures. Time to suckle had a moderate negative correlation (P ≤ 0.05) with both serum glucose and total protein at 24 and 72 h, however did not correlate (P ≥ 0.31) with BUN or NEFA serum concentrations. In conclusion, the initial calf vigor measures were poor predictors of time to suckle; however, time to stand may be a viable vigor measure used to predict calf suckling. Further analysis of immunoglobulin G concentrations in calf serum will be used to determine if these vigor measures have a relationship with passive immune transfer in beef calves. [ABSTRACT FROM AUTHOR]

Multiparous, fall-calving beef cows [n = 48; 649 ± 80 (SD) kg BW; 5.3 ± 0.5 BCS] were individually-fed tall fescue-based hay (12.2% CP, 61.5% NDF) and supplemented to meet/exceed nutrient recommendations except Cu, Zn, and Mn. From approximately 90 d pre-calving to 11 d post-calving, cows received: no additional Cu, Zn, or Mn (CON); Cu, Zn, and Mn sulfates (ITM) or metal methionine hydroxy analogue chelates (CTM, MINTREX®, Novus International) supplying 133% NASEM recommendations; or Cu, Zn, and Mn sulfates and chelates supplying 100% recommendations (reduce and replace, RR). Treatment, sampling day, their interaction, and breeding group were fixed effects with cow as the experimental unit. Colostrum and milk Cu and Mn and plasma Mn were generally not detectable. Colostrum Zn was greater (P ≤ 0.03) in CTM and ITM than CON and RR. All treatments had greater (P < 0.001) colostrum Zn than d 35 milk, which was greater (P ≤ 0.03) than d 60. Treatment did not affect (P ≥ 0.19) cow or calf plasma Cu or Zn post-calving. Calf plasma Zn decreased (P ≤ 0.02) from 0 to 35 d of age. Calf plasma Cu increased (P < 0.01) from 0 to 35 d, then decreased (P = 0.01) from 35 to 60 d. Cow plasma Zn and Cu were greater (P ≤ 0.02) at lactation d 35 and 60 than 1 h post-calving. Pearson correlation coefficients were used to determine relationships among cow and calf mineral status. There were weak positive correlations (P ≤ 0.06) between calf plasma and milk Zn at d 35 and 60. Cow and calf plasma Zn immediately post-calving had a weak negative correlation (P = 0.04). These results indicate greater Zn concentration in beef cow colostrum than milk, and suggest calf circulating Zn is partially dependent on milk Zn concentration. [ABSTRACT FROM AUTHOR]

Our primary objective was to determine the validity of Dairy Herd Improvement Association (DHIA) nutrient composition analysis for beef cow colostrum and milk by comparing DHIA with wet chemistry assays for protein, lactose, and milk urea nitrogen (MUN). A secondary objective was to analyze the change in milk nutrient composition over time in beef cattle. Colostrum and milk were collected from multiparous, fall-calving, Sim-Angus cows [n = 43; BW: 649 ± 80 (SD) kg; BCS: 5.3 ± 0.5; age: 4.3 ± 1.2 yr]. Colostrum was collected from a single rear-quarter pre-suckling, and milk was collected during 4-h milk yields at 35 and 60 d post-calving. Sub-samples were sent for DHIA analysis and frozen for colorimetric assays utilizing commercial kits run on a UV-visible light microplate reader. Analytical methods were compared using a general linear model, and nutrient composition across day was analyzed using a mixed model with day as a repeated effect. When comparing wet chemistry and DHIA colostrum analysis, r2 were 0.142 (P = 0.06), 0.348 (P = 0.002), and 0.0004 (P = 0.91) for protein, lactose, and MUN, respectively. Colostrum protein analyses had a negative relationship, whereas lactose was positive. For 35 d milk, r2 were 0.217 (P = 0.002), 0.128 (P = 0.02), and 0.248 (P = 0.001) for protein, lactose, and MUN, respectively. Comparing 60 d milk, r2 (P < 0.001) were 0.706, 0.314, and 0.381 for protein, lactose, and MUN, respectfully. All milk relationships were positive. There was an effect of day on nutrient concentrations, where colostrum contained greater (P < 0.001) protein than 35 and 60 d milk, whereas lactose and MUN were greatest (P < 0.001) in 35 d milk, and lowest (P < 0.001) in colostrum. These data indicate that beef cow colostrum and milk require wet chemistry analysis for improved accuracy. [ABSTRACT FROM AUTHOR]