Epidemiology of bovine colostrum production in New York Holstein herds: Cow, management, and environmental factors.

Adequate supply of high-quality colostrum is essential for calf health. Colostrum production, at first milking, varies between animals and seasons, but herd-level and management associations with colostrum production have not been well described. Our objectives were to (1) describe colostrum production and colostrum handling practices and (2) to identify individual cow, herd management, and environmental factors associated with colostrum production. A convenience sample of 19 New York Holstein dairy farms (620 to 4,600 cows) were enrolled in this observational study to describe colostrum production and to evaluate cow, management, and prepartum environmental factors associated with colostrum yield and Brix %. Herd owners or managers were given a colostrum management questionnaire, and farm personnel recorded individual colostrum yield and Brix % for primiparous (PP; n = 5,978) and multiparous (MPS; n = 13,228) cows between October 2019 and February 2021. Temperature, relative humidity, and light intensity were measured by sensors placed in each farm's close-up dry cow pens for the entire length of the study. Median colostrum yield for each farm ranged from 2.5 to 7.6 kg for PP and 4.0 to 7.7 kg for MPS cows. Mean Brix % from each farm ranged from 22.2 to 27.9% for PP and 22.0 to 28.8% for MPS cows. Lowest colostrum yield from PP animals was associated with calf sex (female) and colostrum Brix % (≤22%). Greatest colostrum yield from MPS cows was associated with colostrum Brix % (≤22%), calf sex (twin), dry period length (>67 d), gestation length (283-293 d), an alive calf, second parity, previous lactation length (>344 d) and previous lactation 305-d mature equivalent milk yield (>13,091 kg), heat and humidity exposure area under the curve (AUC) 7 d before calving (>69.2 average temperature-humidity index per 30-min interval), and light intensity AUC 14 d before calving (>154.2 average lux per 15-min interval). Greatest colostrum Brix % from PP animals was associated with calf sex (male), an alive calf, and light intensity AUC 14 d before calving (≤64.0 average lux per 15-min interval). Greatest colostrum Brix % from MPS cows was associated with dry period length (>67 d), an alive calf, 305-d mature equivalent milk yield of previous lactation (≤15,862 kg), gestation length (274-282 d), colostrum yield (<6 kg), fifth or greater parity, and heat and humidity exposure AUC 7 d before calving (≤50.1 average temperature-humidity index per 30-min interval). Dairy producers can use this information to recognize the variation in colostrum production and alter colostrum management programs in anticipation of periods of low production or quality.

Effect of rumen-protected branched-chain amino acid supplementation on production- and energy-related metabolites during the first 35 days in milk in Holstein dairy cows.

Essential AA are critical for multiple physiological processes. Branched-chain AA (BCAA) supplementation has beneficial effects on body weight, lipogenesis, and insulin resistance in several species. The BCAA are used for milk and body protein synthesis as well as being oxidized by the tricarboxylic acid cycle to produce ATP during catabolic states. The objective was to evaluate the effect of rumen-protected BCAA (375 g of 27% l-Leu, 85 g of 48% l-Ile, and 91 g of 67% l-Val) with or without propylene glycol (PG) oral administration on milk production, dry matter intake, nonesterified fatty acids, ß-hydroxybutyrate, and plasma urea nitrogen during the first 35 d in milk (DIM) in dairy cattle. Multiparous Holstein cows were enrolled in blocks of three 28 d before expected calving and assigned randomly to either the control or 1 of 2 treatments. The control (n = 26) received 200 g/d of dry molasses, the BCAA treatment (n = 23) received BCAA mixed with 200 g/d of dry molasses from calving until 35 DIM, and the BCAA plus PG (BCAAPG) treatment (n = 25) received BCAA mixed with 200 g/d of dry molasses from calving until 35 DIM plus 300 mL of PG once daily from calving until 7 DIM. Postpartum, dry matter intake least squares means (LSM; 95% confidence interval) were 20.7 (19.9, 21.7), 21.3 (20.4, 22.3), and 21.9 (20.9, 22.8) kg for control, BCAA, and BCAAPG, respectively. Milk yield (1-35 DIM) LSM were 41.7 (39.4, 44.0), 42.7 (40.3, 45.0), and 43.7 (41.4, 46.0) kg for control, BCAA, and BCAAPG, respectively. Energy-corrected milk LSM were 50.3 (46.8, 53.7), 52.4 (48.9, 55.8), and 52.9 (49.5, 56.4) kg for control, BCAA, and BCAAPG, respectively. Milk urea nitrogen LSM in milk for control, BCAA, and BCAAPG were 8.60 (8.02, 9.22), 9.70 (9.01, 10.45), and 9.75 (9.08, 10.47) mg/dL. Plasma urea nitrogen concentrations LSM for control, BCAA, and BCAAPG were 8.3 (7.7, 8.9), 10.1 (9.4, 10.9), and 9.6 (9.4, 10.3) mg/dL, respectively. The numbers of plasma samples classified as hyperketonemia were 77, 44, and 57 in control, BCAA, and BCAAPG, respectively. The BCAA supplementation increased plasma urea nitrogen and milk urea nitrogen, free valine concentration in plasma, and decreased hyperketonemia events during the postpartum period.

Effects of feeding synthetic zeolite A during the prepartum period on serum mineral concentration, oxidant status, and performance of multiparous Holstein cows.

The objective of this study was to determine the effects of feeding synthetic zeolite A for 3 wk before expected calving on peripartal serum mineral concentrations, hypocalcemia, oxidant status, and performance. Holstein cows (n = 55) entering their second or greater lactations were assigned randomly to 1 of 2 dietary treatments starting 21 d before expected calving: control (CON: 40% corn silage, 33% wheat straw, and 27% concentrate; n = 29) or experimental [EXP: CON plus zeolite A (X-Zelit, Protekta Inc., Lucknow, ON, Canada/Vilofoss, Graasten, Denmark; n = 26) at an inclusion rate of 3.3% of dry matter, targeting 500 g/d as-fed]. Cows were fed the same postpartum diet and housed in individual tiestalls through 28 d in milk. Cows fed EXP had higher serum Ca concentrations as parturition approached and during the immediate postpartum period. Serum P concentrations were lower for the EXP-fed cows during the prepartum period and the first 2 d of lactation, whereas serum Mg concentrations were lower than those of the CON-fed cows only during the immediate periparturient period. Cows fed EXP had decreased prevalence of subclinical hypocalcemia (SCH) from d -1 through 3 relative to day of parturition, with the largest difference occurring within the first day postpartum. Prepartum dry matter intake tended to be decreased and rumination was decreased in cows fed EXP; however; postpartum dry matter intake, rumination, milk yield, milk component yield, and colostrum measurements did not differ between treatments. Cows fed EXP tended to have increased hazard of pregnancy by 150 d in milk when controlling for parity compared with CON-fed cows; potential reproductive benefits merit further study. This study demonstrated that zeolite A supplementation during the prepartum period results in markedly improved serum Ca concentrations around parturition and similar postpartum performance compared with controls and is effective at decreasing hypocalcemia in multiparous Holstein cows.

The effect of source of supplemental dietary calcium and magnesium in the peripartum period, and level of dietary magnesium postpartum, on mineral status, performance, and energy metabolites in multiparous Holstein cows.

The objective of this study was to determine the effects of feeding different supplemental sources of Ca and Mg in the peripartum period, and different dietary levels of Mg postpartum, on plasma mineral status, performance, and aspects of energy metabolism in transition dairy cows. Multiparous Holstein cows (n = 41) were used in a completely randomized design with a 2 × 2 factorial arrangement of treatments starting at 28 d before expected parturition. Main effects were source assignments (CS = common sources of supplemental Ca and Mg, or MA = a blend of common and commercial mineral sources with supplemental minerals primarily from a commercial Ca-Mg dolomite source; MIN-AD, Papillon Agricultural Company Inc., Easton, MD) beginning at 21 d before due date; cows were further randomized within source treatments to 1 of 2 levels of Mg supplementation (LM = formulated postpartum diet Mg at 0.30% of dry matter (DM), or HM = formulated postpartum diet Mg at 0.45% of DM) beginning within 1 d after parturition. Final treatment groups included the following: common source, low Mg (CS-LM, n = 11); common source, high Mg (CS-HM, n = 11); MIN-AD, low Mg (MA-LM, n = 10); and MIN-AD, high Mg (MA-HM, n = 9). Treatment diets were fed and data collected through 42 d in milk. Postpartum plasma Mg concentrations tended to be higher for cows fed HM and cows fed CS, but no effects were observed on peripartum plasma Ca concentrations. Peripartum plasma P concentrations were higher for cows fed MA. Dry matter intake (DMI) in the prepartum period was higher for cows fed MA (CS = 15.9 vs. MA = 16.8 kg/d) and postpartum DMI was higher in some groups depending on week. Plasma nonesterified fatty acid concentrations were lower for cows fed MA during both the prepartum and postpartum periods. A source by level interaction was observed for postpartum plasma ß-hydroxybutyrate (BHB) concentrations such that cows fed CS-LM had numerically higher BHB and cows fed MA-LM had numerically lower BHB (geometric means; CS-LM = 7.9, CS-HM = 6.9, MA-LM = 6.3, and MA-HM = 7.3 mg/dL) than cows fed the other 2 treatments. Higher milk fat yield, milk fat content, and fat- and energy-corrected yield during wk 1 for cows fed MA resulted in source by week interactions for these outcomes. This study demonstrated that varying supplemental Ca and Mg sources and feeding rates had minimal effect on plasma Ca status despite differences in plasma Mg and P concentrations. Effects on DMI and plasma energy metabolites suggest an opportunity for strategic use of mineral sources in the transition period to promote metabolic health.

Effects of prepartum dietary cation-anion difference on aspects of peripartum mineral and energy metabolism and performance of multiparous Holstein cows.

The objectives of this study were to determine the effect of decreasing dietary cation-anion difference [DCAD; (Na+ + K+) - (Cl- + S2-)] of the prepartum diet on aspects of mineral metabolism, energy metabolism, and performance of peripartum dairy cows. Multiparous Holstein cows (n = 89) were enrolled between 38 and 31 d before expected parturition and randomized to treatments in a completely randomized design (restricted to balance for previous 305-d mature equivalent milk production, parity, and body condition score) at 24 d before expected parturition. Treatments consisted of a low-K ration without anion supplementation [CON; n = 30, DCAD = +18.3 mEq/100 g of dry matter (DM)]; partial anion supplementation to a low-K ration (MED; n = 30, DCAD = +5.9 mEq/100 g of DM); and anion supplementation to a low-K ration to reach a targeted average urine pH between 5.5 and 6.0 (LOW; n = 29, DCAD = -7.4 mEq/100 g of DM). Cows were fed a common postpartum diet and data collected through 63 d in milk. Urine pH (CON = 8.22, MED = 7.89, and LOW = 5.96) was affected quadratically by decreasing prepartum DCAD. A linear relationship between urine pH and urine Ca:creatinine ratio was observed (r = -0.81). Plasma Ca concentrations in the postpartum period (d 0 to 14; CON = 2.16, MED = 2.19, and LOW = 2.27 mmol/L) were increased linearly with decreasing prepartum DCAD. A treatment by parity (second vs. third and greater) interaction for postpartum plasma Ca concentration suggested that older cows had the greatest response to the low DCAD diet and older cows fed LOW had decreased prevalence of hypocalcemia after calving. A quadratic effect of decreasing DCAD on prepartum DMI was observed (CON = 13.6, MED = 14.0, and LOW = 13.2 kg/d). Milk production in the first 3 wk postpartum was increased linearly with decreasing DCAD (CON = 40.8, MED = 42.4, and LOW = 43.9 kg/d) and DMI in this period also tended to linearly increase (CON = 20.2, MED = 20.9, and LOW = 21.3 kg/d). Overall, effects on intake and milk yield analyzed over wk 1 to 9 postpartum were not significant. This study demonstrates that feeding lower DCAD diets prepartum improves plasma Ca status in the immediate postpartum period and results in increased DMI and milk production in the 3 wk after parturition. Compared with no anion supplementation or lower levels of anion supplementation, greater improvements were observed with the lower DCAD feeding strategy, in which an average urine pH of 5.5 to 6.0 was targeted.

Grape powder attenuates the negative effects of GLP-1 receptor antagonism by exendin-3 (9-39) in a normoglycemic mouse model.

Prediabetes is a condition affecting 35% of US adults and about 50% of US adults age 65+. Foods rich in polyphenols, including flavanols and other flavonoids, have been studied for their putative beneficial effects on many different health conditions including type 2 diabetes mellitus and prediabetes. Studies have shown that some flavanols increase glucagon-like peptide 1 (GLP-1) secretion. GLP-1 is a feeding hormone that increases insulin secretion after carbohydrate consumption, and increased GLP-1 secretion may be responsible for some of the beneficial effects on glycemic control after flavanol consumption. The present study explored the effects of grape powder consumption on metrics of glycemic health in normoglycemic and prediabetic C57BL/6J mice; additionally, the mechanism of action of grape powder polyphenols was investigated. Grape powder significantly reduced (p < 0.01) blood glucose levels following oral glucose gavage after GLP-1 receptor antagonism by exendin-3 (9-39) compared to sugar-matched control, indicating that it was able to attenuate the hyperglycemic effects of GLP-1 receptor antagonism. Grape powder was employed in acute (1.6 g grape powder per kg bodyweight) and long-term high fat diet (grape powder incorporated into treatment diets at 5% w/w) feeding studies in normoglycemic and prediabetic (diet-induced obesity) mice; grape powder did not impove glycemic control in these studies versus sugar-matched control. The mechanisms by which grape powder ameliorates the deleterious effects of GLP-1 receptor antagonism warrant further study.

Effects of monensin and starch level in early lactation diets on indices of immune function in dairy cows.

The objective of this study was to evaluate the effect of dietary starch level and monensin on immune function. Prior to parturition, primiparous (n=21) and multiparous (n=49) Holstein cows were fed a common controlled energy close-up diet with a daily topdress of either 0 or 400 mg/d monensin. From 1 to 21 d in milk (DIM), cows were fed a high-starch (HS; 26.2% starch) or low-starch (LS; 21.5% starch) total mixed ration with a daily topdress of either 0 or 450 mg of monensin/d continuing with prepartum topdress assignment. From 22 through 63 DIM, all cows were fed HS and continued with assigned topdress treatment until 63 DIM. Endometrial cytology and whole-blood immune function were assessed at 8 DIM and on 1 d between 40 and 60 DIM. At 8 DIM, cows fed HS had an increased percentage (%) of phagocytic monocytes and tended to have a greater phagocytosis index (% of positive cells × mean fluorescence intensity) in monocytes compared with cows fed LS. At 8 DIM, cows fed HS also tended to have a higher percentage of monocytes involved in oxidative burst and a higher monocyte oxidative burst index compared with LS cows. At 8 DIM, blood polymorphonuclear neutrophils (PMN) isolated from cows fed monensin during the periparturient period tended to have higher PMN glycogen content compared with control cows. At 40 to 60 DIM, the incidence of cytological endometritis as diagnosed by uterine cytology was not affected by dietary treatment. However, at 40 to 60 DIM, cows fed monensin had an increased percentage of Escherichia coli-stimulated PMN, tended to have a greater percentage of monocytes involved in oxidative burst, and tended to have an increased E. coli-stimulated monocyte oxidative burst index. At 40 to 60 DIM, blood PMN isolated from cows fed HS during early lactation had higher PMN glycogen content compared with cows fed LS during early lactation. Overall, results suggest that feeding higher starch diets postpartum and peripartal supplementation with monensin may have some beneficial effects on immune function, although uterine cytology was not affected by treatment.

Performance of early-lactation dairy cows as affected by dietary starch and monensin supplementation.

The objective of this study was to evaluate the effect of postpartum dietary starch content and monensin supplementation throughout the periparturient period and into early lactation on production performance of dairy cows during early lactation. Prior to parturition, primiparous (n=21) and multiparous (n=49) Holstein cows were fed a common controlled-energy close-up diet with a daily topdress of either 0 or 400mg/d monensin. From d 1 to 21 postpartum, cows were fed a high-starch (HS; 26.2% starch, 34.3% NDF, 22.7% ADF, 15.5% CP) or low-starch (LS; 21.5% starch, 36.9% NDF, 25.2% ADF, 15.4% CP) total mixed ration with a daily topdress of either 0mg/d of monensin or 450mg/d monensin (MON), continuing with prepartum topdress treatment assignment. From d 22 through 63 postpartum, cows were fed HS and continued with their assigned daily topdress. Interactions of starch content and MON supplementation were not significant for any of the variables measured. Cows fed HS from wk 1 to 3 postpartum had higher early-lactation milk yields (starch × week interaction) compared with LS cows, but HS cows also had lower percentages of milk fat, true protein, lactose, and total solids during the same period, resulting in similar yields of energy-corrected milk (ECM) between starch treatments. Cows fed HS had higher early-lactation dry matter intake (DMI; starch × week interaction) and lost less body condition score during wk 1 to 3, contributing to improved energy balance postpartum. No effect of starch treatment was observed on apparent total-tract dry matter or starch digestibilities assessed during d 18 to 19 (±2) postpartum, although cows fed the LS diet had greater apparent total-tract NDF digestibility compared with cows fed the HS diet. Cows fed MON had higher DMI and higher milk yields during the first 9 wk of lactation. However, all cows had similar yields of ECM because of trends for lower milk fat content during early lactation. In part because of similar yields of ECM between these treatments and higher DMI for cows fed MON, ECM per DMI during the first 9 wk of lactation was not affected by MON treatment. There was no effect of MON treatment on apparent total-tract dry matter, NDF, or starch digestibilities. Overall, cows fed more propiogenic diets in early lactation (HS or MON) had increased milk yield and DMI during the immediate postpartum period, indicating that diets with greater propiogenic capacity do not have detrimental effects on early-lactation DMI.

Metabolism of early-lactation dairy cows as affected by dietary starch and monensin supplementation.

The objective of this study was to evaluate the effect of dietary starch content and monensin (MON) on metabolism of dairy cows during early lactation. Before parturition, primiparous (n=21) and multiparous (n=49) Holstein cows were fed a common controlled-energy close-up diet with a daily topdress of either 0 or 400mg/d monensin. From d 1 to 21 postpartum, cows were fed a high-starch (HS; 26.2% starch, 34.3% neutral detergent fiber, 22.7% acid detergent fiber, 15.5% crude protein) or low-starch (LS; 21.5% starch, 36.9% neutral detergent fiber, 25.2% acid detergent fiber, 15.4% crude protein) total mixed ration with a daily topdress of either 0mg/d monensin (CON) or 450mg/d monensin (MON), continuing with prepartum topdress assignment. From d 22 through 63 postpartum, all cows were fed HS and continued with the assigned topdress treatment until d 63. Cows fed HS had higher plasma glucose and insulin and lower nonesterified fatty acids (NEFA) than cows fed LS during d 1 to 21 postpartum. Cows fed LS had elevated early-lactation ß-hydroxybutyrate (BHBA) compared with cows fed HS. Cows fed HS had greater insulin resistance and increased plasma haptoglobin in the early lactation period. There was no effect of MON on postpartum plasma NEFA. Cows fed MON had higher plasma glucose compared with CON cows, which was driven by a MON × parity interaction in which primiparous cows fed MON had greater plasma glucose concentrations than cows fed CON. Cows fed MON had lower plasma BHBA compared with CON, which was contributed to by a MON × parity interaction in which primiparous cows fed MON had lower BHBA concentrations than CON. Starch treatment had no effect on overall liver triglyceride content. Primiparous cows fed MON had increased liver triglyceride content compared with CON primiparous cows, and multiparous cows fed MON had decreased liver triglyceride content compared with CON cows. Multiparous cows fed LS with MON had higher liver glycogen content than multiparous cows fed the LS without MON, with no effect of MON treatment for multiparous cows fed HS. There was no effect of starch or MON treatment on liver capacity to oxidize propionate to CO2, and effects of starch on gluconeogenesis were not significant. Cows fed MON tended to have greater capacity to convert propionate to glucose than CON. Supplementation with MON increased the ratio of glucose to CO2, which indicated that cows fed MON had a greater propensity to convert propionate to glucose. Overall, cows fed more propiogenic diets in early lactation (high starch or monensin) exhibited improved energy metabolism during early lactation.

Effects of chromium propionate supplementation during the periparturient period and early lactation on metabolism, performance, and cytological endometritis in dairy cows.

Multiparous Holstein cows (n=61) were used to determine the effects of chromium propionate (Cr-Pro) supplementation during the periparturient period and early lactation on metabolism, performance, and the incidence of cytological endometritis (CE). After a 1-wk preliminary period, cows were assigned randomly to 1 of 2 treatments from 21 d before expected calving through 63 d postpartum: (1) control (n=31) and (2) Cr-Pro (n=30) administered by daily topdress at a rate of 8 mg/d of Cr. A tendency was detected for increased dry matter intake (DMI) during the prepartum period for cows fed Cr-Pro. Moreover, cows fed Cr-Pro tended to have lower plasma concentrations of nonesterified fatty acids during the prepartum period. However, effects of Cr-Pro supplementation on postpartum DMI and milk yield were not significant. Cows fed Cr-Pro tended to have higher urea N concentrations in milk. An interaction of treatment and day existed during the postpartum period, such that cows fed Cr-Pro had lower plasma glucose concentrations within the first day postpartum compared with controls. Plasma haptoglobin concentration was not affected by treatment during the postpartum period. Blood neutrophil glycogen concentrations were not affected by treatment when sampled at either 7 d postpartum or on one day between 40 and 60 d (48 d ± 0.44 standard error) postpartum. Evaluation of endometrial cytology by low volume lavage at 7 d postpartum (first lavage) and on one day between 40 and 60 d (second lavage) postpartum revealed that cows fed Cr-Pro tended to have a higher percentage of neutrophils at first lavage and decreased incidence of CE as assessed at second lavage. In conclusion, supplementation with Cr-Pro resulted in trends for increased DMI and lower plasma nonesterified fatty acids prepartum. Postpartum production and energy metabolism were not affected by treatment; however, Cr-Pro supplementation tended to affect the postpartum influx of neutrophils into the uterus and decreased the incidence of CE, suggesting positive effects of Cr-Pro supplementation on uterine health.

Effects of hydroxy trace minerals on oxidative metabolism, cytological endometritis, and performance of transition dairy cows.

Multiparous Holstein cows (n=60) were used to determine effects of supplementing hydroxy forms of Zn, Cu, and Mn compared with 2 other common supplementation strategies on oxidative metabolism, cytological endometritis, and performance of transition cows. After a 1-wk pretreatment period, cows were assigned randomly to 1 of 3 dietary treatments from 21 d before expected calving through 84 d postcalving. Dietary treatments administered by daily top-dressing included (1) inorganic sulfate forms of Zn, Cu, and Mn (ITM); (2) a blend (75:25) of sulfates and organic complexes of Zn, Cu, and Mn (ITM/OTM); and (3) hydroxy trace minerals (HTM) of Zn, Cu, and Mn. The resulting dietary concentrations of supplemental Zn, Cu, and Mn were similar among treatments and averaged 40, 10, and 27 mg/kg, respectively, before calving and 59, 15, and 40 mg/kg, respectively, after calving. Total concentrations of Zn, Cu, and Mn averaged 80, 16, and 62 mg/kg during the prepartum period and 102, 23, and 75 mg/kg, respectively, during the postpartum period. Overall, effects of treatment on milk yield and milk composition were not significant. Cows fed HTM during the prepartum period had higher body weight (BW) than those fed ITM during the prepartum period and had higher BW during the postpartum period than those fed the other treatments; however, BW change, body condition score, and body condition score change were not affected by treatment. Plasma total antioxidant capacity was lower in cows fed HTM than ITM but was not different from cows fed ITM/OTM. Cows fed HTM tended to have lower concentrations of plasma thiobarbituric acid reactive substances than those fed ITM during the whole study period, but plasma thiobarbituric acid reactive substances were not different between HTM and ITM/OTM. Plasma haptoglobin was lower in cows fed HTM than ITM/OTM at 1 wk postpartum. Endometrial cytology 7d postcalving and cytological endometritis as assessed on 1d between 40 and 60 d postcalving was not affected by treatment. In conclusion, supplementation with HTM sources of Zn, Cu, and Mn modulated plasma variables related to oxidative metabolism compared with supplementation with ITM; however, HTM and ITM/OTM resulted in similar responses. Furthermore, the source of trace minerals did not affect performance or uterine health in this experiment.

Phosphorus feeding levels and critical control points on dairy farms.

A viable and cost-effective approach to managing P on dairy farms is to minimize excess P in diets, which in turn leads to less excretion of P in manure without impairing animal performance. A questionnaire survey was conducted, coupled with on-site feed and fecal sample collection and analysis on dairy farms in New York, Pennsylvania, Delaware, Maryland, and Virginia. The purpose was to assess dietary P levels and to identify critical control points pertaining to P feeding management. Survey responses, 612 out of 2500 randomly selected farms, revealed a wide range of dietary P concentrations for lactating cows, from 3.6 to 7.0 g/kg of feed DM. The mean was 4.4 g/kg, which was 34% above the level recommended by the NRC for 27.9 kg milk/d, the mean milk yield in the survey. Higher P concentrations in diets were not associated with higher milk yields (n = 98, R2 = 0.057 for the survey farms; n = 92, R2 = 0.043 for farms selected for on-site sampling). However, higher dietary P led to higher P excretion in feces (n = 75, R2 = 0.429), with much of the increased fecal P being water soluble. Phosphorus concentrations in diet samples matched closely with P concentrations in formulated rations, with 67% of the feed samples deviating <10% from the formulations. On 84% of the survey farms, ration formulation was provided by professionals rather than producers themselves. Most producers were feeding more P than cows needed because it was recommended in the rations by these consultants. In conclusion, P fed to lactating cows averaged 34% above NRC recommendations; to reduce excess dietary P, ration formulation is the critical control point.

Emergency management of major hydrofluoric acid exposures.

Exposures of as little as 2.5 per cent of the body surface to concentrated hydrofluoric acid (HF) may be fatal. Survival after major HF exposures is facilitated by aggressive emergency management which, we feel, includes wound irrigation, subeschar injection of calcium gluconate, monitored supplementation of serum calcium, and prompt wound excision carried out as an emergency procedure. The following case reports and literature review illustrate the important differences between exposures to concentrated HF of as little as 2 per cent of the body surface and smaller exposures to concentrated HF or exposure to dilute HF.