Negative dietary cation-anion difference and amount of calcium in prepartum diets: Effects on urine and serum minerals.

Negative dietary cation-anion difference (DCAD) diets fed prepartum induce a compensated metabolic acidosis, which stimulates metabolic Ca flux before calving and decreases clinical and subclinical hypocalcemia after calving. Effects of low or high dietary Ca in these diets are unclear. Our objective was to determine the effects of inducing a prepartum metabolic acidosis and the amount of dietary Ca on urinary mineral excretion and serum mineral concentrations during the transition period in multiparous Holstein cows (n = 81). Treatment diets fed during the last 28 d before calving were (1) positive DCAD, +6 mEq/100 g of dry matter (DM), target urine pH >7.5, low dietary Ca (0.40% DM; CON); (2) negative DCAD, -24 mEq/100 g of DM, target urine pH 5.5 to 6.0, low dietary Ca (0.40% DM; ND); or (3) negative DCAD, -24 mEq/100 g of DM, target urine pH 5.5 to 6.0, high dietary Ca (2.0% DM; NDCA). Urine was sampled on -21, -14, -7, +1, +2, and +7 d relative to calving. Blood samples were collected on d -30, -21, -14, -7, -4, -2, -1, 0, 1, 2, and 4 relative to parturition. Preplanned treatment contrasts were (1) CON versus ND and NDCA, and (2) ND versus NDCA. Cows fed ND or NDCA had increased urinary volume and excretion of Ca, Cl, and SO4-2, along with decreased excretion of K. Supplementation of Ca to the acidogenic diet increased urinary excretion of Ca at d -21, but this difference lessened as cows approached parturition. Additional Ca increased prepartum urinary excretion of K and Cl. Differences in excretion decreased quickly after parturition, although urinary excretion of Cl remained greater for cows previously fed negative DCAD diets. Acidogenic diets increased serum K and Cl concentrations prepartum. Supplemental Ca decreased serum P relative to ND. During d 0 to 4, serum P and K were greater for cows fed ND or NDCA than for cows fed CON; these differences disappeared by d 4. Acidogenic diets increased serum Ca by increasing Ca flux and excretion in urine. Supplemental Ca in the acidogenic diet modestly increased Ca excretion early in the close-up period.

Metabolic and blood acid-base responses to prepartum dietary cation-anion difference and calcium content in transition dairy cows.

Dairy cows commonly undergo negative Ca balance accompanied by hypocalcemia after parturition. A negative dietary cation-anion difference (DCAD) strategy has been used prepartum to improve periparturient Ca homeostasis. Our objective was to determine the influence of a negative DCAD diet with different amounts of dietary Ca on the blood acid-base balance, blood gases, and metabolic adaptation to lactation. Multiparous Holstein cows (n = 81) were blocked into 1 of 3 dietary treatments from 252 d of gestation until parturition: (1) positive DCAD diet and low Ca (CON; containing +6.0 mEq/100 g DM, 0.4% DM Ca); (2) negative DCAD diet and low Ca (ND; -24.0 mEq/100 g DM, 0.4% DM Ca); or (3) negative DCAD diet plus high Ca supplementation (NDCA; -24.1 mEq/100 g DM, 2.0% DM Ca). There were 28, 27, and 26 cows for CON, ND, and NDCA, respectively. Whole blood was sampled at 0, 24, 48, and 96 h after calving for immediate determination of blood acid-base status and blood gases. Serum samples collected at -21, -14, -7, -4, -2, -1, at calving, 1, 2, 4, 7, 14, 21, and 28 d relative to parturition were analyzed for metabolic components. Results indicated that cows fed ND or NDCA had lower blood pH at calving but greater pH at 24 h after calving compared with CON. Blood bicarbonate, base excess, and total CO2 (tCO2) concentrations of cows in ND and NDCA groups were less than those of cows in CON at calving but became greater from 24 to 96 h postpartum. The NDCA cows had lower blood bicarbonate, base excess, and tCO2 at 48 h and greater partial pressure of oxygen after calving compared with ND. Cows fed ND or NDCA diets had lower serum glucose concentrations than CON cows before calving but no differences were observed postpartum. Serum concentrations of total protein and albumin were greater prepartum for cows in ND and NDCA groups than for those in CON. Postpartum serum urea N and albumin concentrations tended to be higher for ND and NDCA cows. Cows fed ND or NDCA diets had elevated serum total cholesterol concentration prepartum. During the postpartum period, triglycerides and NEFA of cows fed ND or NDCA diets tended to be lower than those of CON. Cows fed the NDCA diet had greater postpartum total cholesterol in serum and lower NEFA concentration at calving than ND. In conclusion, feeding a prepartum negative DCAD diet altered blood acid-base balance and induced metabolic acidosis at calving, and improved protein and lipid metabolism. Supplementation of high Ca in the negative DCAD diet prepartum was more favorable to metabolic adaptation to lactation in dairy cows than the negative DCAD diet with low Ca.

Effects of feeding frequency and protein source in milk replacer for Holstein calves.

Whey proteins are a primary component of milk replacers (MR) and are considered the gold standard for calves. Alternative protein sources may decrease MR cost if calf performance is similar. A blend of bovine plasma protein and modified wheat protein might be a good partial replacement for whey protein. Usually MR is fed twice daily, but feeding 3 times daily might increase efficiency of nutrient use, especially with MR containing alternate proteins. Therefore, our objective was to determine the effects of 2 MR, containing either entirely whey protein (CON) or a combination of whey protein, bovine plasma protein, and modified wheat protein (WBP), when fed in either 2 or 3 meals daily on calf growth and health. Female and male Holstein calves (n = 103) housed in individual hutches were studied for the first 63 d of life, with additional measurements obtained at wk 12 of life in group housing. The MR contained 25% CP, 17% fat, and a Lys:Met ratio of 3.1:1. Individual treatments arose from the 2 × 2 factorial arrangement of MR formulation and frequency of feeding. After colostrum, calves were fed MR (12.5% solids) at daily rates of dry matter dependent on age. Amounts were as follows: d 3 to 10 = 0.52 kg/d (2× = 0.259 kg, 3× = 0.173 kg per feeding); d 11 to 20 = 0.68 kg/d (2× = 0.341 kg, 3× = 0.227 kg per feeding); d 21 to 42 = 0.84 kg/d (2× = 0.42 kg, 3× = 0.28 kg per feeding); d 43 to 46, 47, 49, and 51 = 0.42 kg/d, with both 2× and 3× changed to 1 feeding daily and skip days (d 48 and 50) between where calves were not given MR; and d 52 = calves weaned. Starter was fed and intake was measured from d 1 until d 63. Intakes, health scores, attitude scores, and fecal scores were measured daily. Body weight (BW) and growth measurements were obtained weekly until wk 8 and again at wk 12. Blood samples were obtained at 0, 24, and 48 h and then on d 5, 14, 28, and 42 of age. Starter intake was greater for calves fed WBP versus CON during wk 7 to 9. Final BW and hip width at wk 12 were greater for calves fed WBP than for calves fed CON. Calves fed 2× had greater mean and final BW to wk 6 and greater feed efficiency (gain:feed ratio) than calves fed 3×. Blood variables supported the generally similar growth outcomes. Health outcomes did not differ between diets or feeding frequencies. Overall, calves fed WBP had increased starter intake and greater BW gains during wk 7 to 12 than calves fed CON, and calves fed 2× had increased growth and feed efficiency compared with those fed 3×.

Negative dietary cation-anion difference and amount of calcium in prepartum diets: Effects on milk production, blood calcium, and health.

Acidogenic prepartum diets with negative dietary cation-anion difference (DCAD) induce compensated metabolic acidosis, which stimulates calcium (Ca) mobilization before calving and decreases clinical and subclinical hypocalcemia postpartum. This strategy is often combined with limiting dietary Ca concentrations, which historically has been used to mobilize Ca prepartum to prepare cows for lactation. Supplemental dietary Ca in combination with a negative DCAD formulation that does not reverse the effect of compensated metabolic acidosis may be beneficial. Our objective was to determine the effects of prepartum dietary strategies on dry matter intake (DMI), milk production, peripartal Ca status, and health during the transition period in multiparous Holstein cows (n = 81). Treatments during the last 28 d before calving were: (1) positive DCAD diet, +6 mEq/100 g of DM, target urine pH >7.5, low dietary Ca (0.40% DM; CON); (2) negative DCAD diet, -24 mEq/100 g of DM, target urine pH 5.5 to 6.0, low dietary Ca (0.40% DM; ND); or (3) negative DCAD diet, -24 mEq/100 g of DM, target urine pH 5.5 to 6.0, , high dietary Ca (2.0% DM; NDCA). Preplanned treatment contrasts were: (1) CON versus (ND and NDCA), and (2) ND versus NDCA. Individual DMI were recorded daily. Cows were milked 3 times daily, with individual DMI and milk yield summarized by week. Whole blood sampled at calving and 24 h, 48 h, and 4 d after calving was analyzed for ionized Ca concentration, and serum was analyzed for total Ca. Prepartum urine pH for cows fed ND or NDCA averaged 5.7, whereas cows fed CON remained >7.5. During the 3 wk before calving, cows fed CON had greater DMI than cows fed ND or NDCA, with NDCA greater than ND. Postpartum DMI (% of body weight) tended to be less for cows fed CON than for those fed ND or NDCA prepartum. Thresholds for subclinical hypocalcemia were ionized Ca <1.0 mM at 24 h, and total Ca ≤2.125 mM at 48 h after calving. On average, blood Ca for cows fed CON indicated subclinical hypocalcemia, whereas blood Ca for cows fed ND or NDCA was greater than subclinical hypocalcemia thresholds for both ionized Ca and total Ca. No milk production differences were detected. Cows fed CON had an elevated adverse health score (calculated by assigning numerical values to recorded health events) and tended to have an elevated somatic cell count during the fresh period compared with cows fed ND or NDCA. Overall, an acidogenic diet prepartum without or with high Ca improved postpartum Ca status and health. Supplementation of additional Ca to the acidogenic diet had little effect.

Increased dietary calcium inclusion in fully acidified prepartum diets improved postpartum uterine health and fertility when fed to Holstein cows.

The objective of this study was to determine the effects of prepartum negative dietary cation-anion difference diet (DCAD) fed at two dietary Ca inclusion rates on postpartum uterine health and ovulation dynamics of multiparous Holstein cows (n = 76). Treatments began at 28 days before expected calving until parturition and were: CON: DCAD = +6 mEq/100g of DM with low dietary Ca (46.2 ± 15.2 g Ca/d; 0.4% DM; n = 26); ND: DCAD = -24 mEq/100g of DM with low dietary Ca (44.1 ±â€¯16.1 Ca/d; 0.4% DM; n = 24); NDCA: DCAD = -24 mEq/100g of DM with high dietary Ca (226.6 ±â€¯96.0 g Ca/d; 2.0% DM; n = 26). Vaginal discharge was evaluated through the fresh period via Metricheck (MC) for presence of purulent material. Polymorphonuclear (PMN) cell concentration in the uterus was evaluated at 15 and 30 days relative to calving (DRC). Endometrial tissue was harvested at 30 DRC for glandular morphology, presence of tight-junctions and adheren-junctions proteins, as well as assessment of superoxide dismutase (SOD) and glutathione peroxidase (GPX) activity. Blood plasma and serum samples were harvested in the prepartum and postpartum phase and were assessed for concentrations of lipopolysaccharide binding protein (LBP), serum amyloid A (SAA), and haptoglobin (HP). Ovarian dynamics were assessed through the fresh period until first timed artificial insemination (TAI). Cows fed CON had a lower MC score (P = 0.06) than the average of cows fed ND and cows fed NDCA. Cows fed ND had a higher MC score than cows fed NDCA. Cows fed NDCA had greater uterine gland epithelial height (P = 0.02) than cows fed ND. Cows fed NDCA also had a greater number of epithelial cells per gland (P = 0.05) than cows fed ND. Cows fed NDCA had greater intensity of occludin expression (P = 0.15) than cows fed ND. Cows fed NDCA had increased activity of SOD (P = 0.05) and decreased activity of GPX (P < 0.001) than cows fed ND. Cows fed ND had higher plasma HP concentrations than cows fed NDCA in the prepartum (P = 0.01) and post-partum (P = 0.03) periods. Cows fed ND and NDCA had lower (P = 0.01) postpartum plasma HP concentration than cows fed CON. In conclusion, cows fed NDCA had an improved uterine environment most likely due to alleviation of oxidative stress, an enhanced immune response to parturition and uterine discharge comparable to cows fed CON.

Effect of supplementing pasteurized milk balancer products to heat-treated whole milk on the growth and health of dairy calves.

Two experiments were conducted to determine the growth and health effects of supplementing heat-treated whole milk with pasteurized milk balancer products in calf-feeding programs. All calves were removed from their dams at birth (d 0), fed 3.8L of heat-treated colostrum, and received assigned treatments from d 1 until weaning at d 56. Calves were weighed and skeletal measurements taken every 7 d from d 0 until 56. Average daily gain (ADG) and feed efficiency (FE) were calculated. In experiment 1, 80 Holstein heifer calves were used to investigate the effects of supplementing 2 levels of heat-treated whole milk with or without a pasteurized all-milk balancer. Four dietary treatments (n=20) were used. Calves receiving milk (M) and milk plus balancer (M+B) were fed 3.8L of milk divided into 2 equal feedings daily. Calves fed increased milk (IM) and increased milk plus balancer (IM+B) received 3.8L of milk divided into 2 equal feedings from d 1 to 14, 5.7L from d 15 to 42, and 2.85L fed once daily from d 43 to 56. Treatments M+B and IM+B included pasteurized all-milk balancer fed at a rate of 0.23kg per 3.8L of milk. In experiment 2, 72 Holstein heifer calves were used to investigate the effects of supplementing either a pasteurized all-milk balancer or a pasteurized protein-blend milk balancer. Three dietary treatments (n=24) were used. Calves were fed 3.8L of milk divided into 2 equal feedings from d 1 to 14 and 5.7L from d 15 to 56. Treatment IM did not include any supplements. Balancer was added to IM+B and increased milk plus protein-blend balancer (IM+PB). Balancer was supplemented at a rate of 0.23kg per 3.8L of milk. In experiment 1, calves fed IM+B had greater average body weight (BW) and average daily gain compared with calves given other treatments. Calves fed 5.7L of milk had greater FE than those fed 3.8L regardless of balancer added. In experiment 2, calves fed IM+B and IM+PB had greater BW when compared with calves given M. Calves fed IM+PB had comparable BW and FE to calves given IM+B. The enhanced calf-feeding programs evaluated in this study were successful in increasing growth in preweaned calves when supplementing milk balancer product to heat-treated whole milk. Health scores of fecal, respiratory, and attitude determined illness. Feces were looser for calves receiving IM+B and IM+PB, but attitude scores did not confirm an illness and so overall health was not different between treatments.