Effects of anion supplementation to low-potassium prepartum diets on macromineral status and performance of periparturient dairy cows.

Data from multiparous Holstein cows (n = 43) were used to determine whether supplementation of anions to low-potassium (K) prepartum diets would improve periparturient energy and macromineral status and affect performance during the postpartum period. Beginning 21 d before expected parturition, cows were fed a control diet (1.29% K; +10 mEq/100 g; n = 21) or a low dietary cation-anion difference (DCAD) diet (1.29% K; -15 mEq/100 g; n = 22) with anions provided through a combination of sulfate from calcium sulfate dihydrate (0.40% S total ration) and chloride (1.17% Cl total ration) from SoyChlor 16-7 (West Central, Ralston, IA). All cows were fed the same postpartum diet from parturition through 63 d postpartum. Feeding anions decreased overall urine pH (8.17 vs. 6.70) during the prepartum period. Overall, peripartum concentrations of plasma Ca, P, and Mg were similar between treatments; however, concentrations of plasma Ca tended to be increased during the first 24 h postcalving in cows fed the low DCAD diet. Overall, concentrations of plasma P tended to be increased by feeding the anionic diet prepartum; this effect was more pronounced during the immediate peripartal period. Anionic supplementation did not affect incidence of clinical (<5 mg/dL) and subclinical (5 to 8 mg/dL) hypocalcemia, clinical hypophosphatemia (<2 mg/dL), or clinical (<1.1 mg/dL) and subclinical (1.1 to 1.8 mg/dL) hypomagnesemia. Nevertheless, subclinical hypophosphatemia (2 to 4 mg/dL) tended to be decreased at 16 h postcalving and was decreased at d 2 postpartum for cows fed the anionic diet prepartum. Anion supplementation decreased prepartum dry matter intake (15.6 vs. 14.4 kg/d), but did not affect postpartum dry matter intake (22.4 vs. 23.0 kg/d), milk yield (46.5 vs. 46.1 kg/d), or content and yield of milk fat and true protein. Plasma concentrations of energy-related metabolites (glucose, nonesterified fatty acids, beta-hydroxybutyrate) were similar for both groups during the prepartum and postpartum periods. Glucose rate of appearance was determined by continuous infusion of 6,6-dideuterated glucose in a subset of cows between 6 and 10 d prepartum (control, n = 12; low DCAD, n = 9) and 7 and 10 d postpartum (control, n = 9; low DCAD, n = 8) periods. Glucose rate of appearance was not affected by treatment during the prepartum or postpartum periods. Overall, anion supplementation of low K diets improved P status during the early postpartum period, but did not affect aspects of energy metabolism or periparturient performance.

The relative merit of ruminal undegradable protein from soybean meal or soluble fiber from beet pulp to improve nitrogen utilization in dairy cows.

Early lactating dairy cows were used to determine whether the replacement of solvent-extracted soybean meal [SSBM; a source of rumen-degradable protein (RDP)] with expeller soybean meal (ESBM; a source of rumen-undegradable protein), or the replacement of high-moisture shelled corn (HMSC) with beet pulp (a source of soluble fiber) would be effective in improving efficiency of N usage for milk production. The study was designed as a replicated 4 x 4 Latin square with 21-d periods. Eight multiparous Holstein cows were fed, ad libitum, the following diets, which were based on alfalfa silage and HMSC, and formulated to be isocaloric: 1) basal diet without a protein supplement (negative control diet: NC); 2) NC supplemented with solvent-extracted SBM (diet SSBM); 3) NC supplemented with expeller SBM (diet ESBM); 4) SSBM in which unmolassed dried beet pulp replaced half of the HMSC (diet SSBMBP). Compared with diet NC, protein supplementation increased intake of organic matter and dry matter. Milk and milk protein yields were lower with NC but this diet resulted in the greatest efficiency of N usage for milk production (30% milk N/N intake). Supplementation with ESBM, a proven source of RUP, increased plasma concentrations of histidine and branched-chain amino acids, and reduced milk urea N concentration, but failed to improve the yields of milk or milk protein. Milk fat yield tended to decrease with RUP supplementation. Replacing part of HMSC with soluble fiber from beet pulp (SSBMBP) tended to decrease milk production compared with SSBM; the effect was due to a reduction in dry matter intake. There were no differences among diets SSBM, ESBM, or SSBMBP in urinary excretion of purine derivatives. Neither substitution of ESBM for SSBM nor partial replacement of HMSC with beet pulp altered the efficiency of N usage for milk production or manure N excretion.

Towards non-invasive methods to determine the effect of treatment of soya-bean meal on lysine availability in dairy cows.

Lysine (Lys) availability in three different soya-bean meal (SBM) products was determined using the following techniques: whole body (WB) net flux of Lys, digestible Lys (duodenal flow × intestinal digestibility) and the plasma Lys response curve method of Rulquin and Kowalczyk (2003). Four multiparous Holstein cows (173 days in milk) were equipped with ruminal and duodenal cannulas and used in a 4 × 4 Latin square experiment with 14-day periods. The animals were fed either solvent-extracted SBM (SE), expeller-processed SBM (EP) or lignosulphonate-treated SBM (LS) at 23% of the diet dry matter (DM). The fourth treatment (SE70) consisted of a continuous infusion of Lys (70 g/day) into the omasum of cows fed the SE diet. Chromium(III) oxide was included as a digesta marker in order to determine the duodenal flow of amino acids (AA). On day 12 of each experimental period, six blood samples were collected to determine plasma Lys concentrations. Immediately after that, a pulse dose of L-[2-15N] Lys was administered in the jugular vein. Jugular blood samples were then collected at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 16, 19, 25 and 31 min after the injection to determine 15N Lys enrichment. On each of days 13 and 14, eight digesta samples were collected and pooled by period. Amongst the diets of SBM (SE, EP, LS), no differences were observed for duodenal Lys flow or digestible Lys. Duodenal flow of microbial N with SE was numerically higher, compared with EP and LS, indicating enhanced duodenal supply of microbial Lys for this diet, and this may have compensated for the additional Lys derived from undegradable protein in rumen-protected SBM products (EP and LS). The use of the plasma response curve method as well as the measurement of WB Lys flux also revealed no differences in Lys availability among the SBM products. The WB flux method resulted in 100% post-ruminal recovery of the Lys infused with diet SE70 compared with the control diet SE, which indicates that the method is reliable for determining Lys availability. The Lys flux approach not only allows for the estimation of intestinally available essential AA but also it avoids the use of cannulated animals.

Effect of timing of Cosynch on fertility of lactating Holstein cows after first postpartum and Resynch timed-AI services.

To compare two intervals from the PGF(2alpha) injection to the second GnRH injection+timed artificial insemination (TAI) of Ovsynch, lactating Holstein cows received their first postpartum TAI after Presynch + Ovsynch (n=352) and second and greater postpartum TAI after resynchronization of ovulation using Ovsynch (Resynch; n=458). Each week, cows housed in each of four breeding pens were randomized by breeding pen to receive the second GnRH injection of Presynch + Ovsynch or Resynch and TAI either 48 h (Cosynch 48; n=382) or 72 h (Cosynch 72; n=428) after the PGF(2alpha) injection of Ovsynch or Resynch. Overall, pregnancies per AI (P/AI) did not differ for cows receiving Cosynch 48 (29%) versus Cosynch 72 (33%). Furthermore, treatment did not affect P/AI for cows receiving first postpartum TAI after Presynch + Ovsynch, for cows receiving second and greater TAI after Resynch, or the proportion of female calves born. In conclusion, delaying the second GnRH injection and TAI from 48 to 72 h after the PGF(2alpha) injection of Ovsynch did not affect P/AI or calf sex ratio. The lack of a difference in fertility between these Cosynch protocols may offer more flexibility for implementing a systematic synchronization protocol when a Cosynch strategy is used.

Ruminal degradability and intestinal digestibility of protein and amino acids in treated soybean meal products.

Four lactating dairy cows equipped with ruminal and duodenal cannulas were used to determine the impact of different methods of treating soybean meal (SBM) on the ruminal degradability and intestinal digestibility of crude protein and AA. Solvent-extracted SBM (SE), expeller SBM (EP), lignosulfonate SBM (LS), and heat and soyhulls SBM (HS) were incubated in the rumen in nylon bags for 48, 24, 16, 8, 4, 2, and 0 h according to National Research Council (2001) guidelines. Additional samples of each SBM product were also incubated for 16 h in the rumen; the residues from these bags were transferred to mobile bags, soaked in pepsin HCl, and then used for determination of intestinal digestibility in situ or in vitro. Treatment of SBM (EP, LS, HS) protected the crude protein and AA from ruminal degradation, increasing rumen undegradable protein from 42% in SE to 68% in EP. Kinetic analysis of crude protein and AA degradation in the rumen revealed that, compared with LS and HS, EP exhibited slower rates of degradation but a shorter lag phase and a higher proportion of soluble protein. For all SBM products, the pattern of ruminal degradation, at 16 h of incubation, was characterized by extensive degradation of Lys and His, whereas Met and the branched-chain AA were degraded to the least extent. Estimates of intestinal digestibility of AA and crude protein were lower when measured in vitro than in situ; the magnitude of the difference between the 2 methods was greater (25%) with treated SBM products than with SE (10%). The availability of essential and nonessential AA was consistently greater (30%) with treated SBM than with SE. Among the treated SBM products, 4 essential AA (Ile, Leu, Phe, and Val) showed differences in availability, with values consistently lower for HS than for LS. This study showed that, based on in situ measures, heat and chemical treatment of SBM enhanced AA availability, and that compared with HS, EP and LS had a higher potential to enhance the AA supply to the small intestine of high-producing dairy cows.

Feeding glycerol to transition dairy cows: effects on blood metabolites and lactation performance.

Glycerol can alleviate the symptoms of ketosis when delivered as an oral drench. The addition of glycerol to the diet would eliminate the need for restraining cows for drenching yet deliver a glucogenic substrate, alleviate the fatty liver-ketosis complex, and improve lactational performance. For this study, 21 multiparous and 9 primiparous Holstein cows blocked by parity and expected calving date were used in a randomized block design to evaluate the effects of feeding glycerol from 14 d prepartum to 21 d in milk (DIM). Treatments (kg/d dry matter basis) were 0.86 of cornstarch (control), 0.43 cornstarch + 0.43 glycerol (LG), or 0.86 glycerol (HG), topdressed and hand-mixed into the upper one-third of the daily ration. All cows were fed a common diet from 22 to 70 DIM. Prepartum dry matter intake (DMI) was greater for cows fed the control diet compared with LG or HG (13.3, 10.8, and 11.3 +/- 0.50 kg/d, respectively). Prepartum plasma glucose, insulin, beta-hydroxybutyrate, nonesterified fatty acids, and ruminal profiles were not affected by treatments. Rumen fluid collected postpartum from cows fed LG and HG had greater total volatile fatty acids, greater molar proportions of propionate, and a decreased ratio of acetate to propionate. Furthermore, concentrations of butyrate tended to be greater in rumens of cows fed LG and HG. Postpartum concentrations of glucose in plasma were greatest for cows fed the control diet relative to LG and HG (66.0 vs. 63.1 and 58.4 mg/dL, respectively) and decreased sharply at 21 DIM, after treatments ended, for cows fed HG (diet x day interaction). Body weight and condition loss, plasma nonesterified fatty acids, and liver lipids during the first 21 DIM were similar among treatments. Postpartum DMI was not affected by treatments; however, a tendency was observed for a diet x day interaction for body weight, as cows fed LG gained more body weight from 21 to 70 DIM relative to cows fed HG. Yield of energy-corrected milk during the first 70 DIM tended to be greatest for cows fed the control diet. The LG and HG diets decreased urea nitrogen concentrations in milk relative to controls. Based upon prepartum DMI and concentrations of glucose and beta-hydroxybutyrate in blood postpartum, feeding glycerol to dairy cows at the levels used in this experiment increased indicators used to gauge the degree of ketosis in dairy cattle.

Effect of prepartum dietary protein level on performance of primigravid and multiparous Holstein dairy cows.

This study compared the effects of two levels of crude protein (CP) fed during late gestation on the performance, blood metabolites, and ovarian activity of Holstein cows. One-hundred and six cows (42 primigravid and 64 multiparous) 32 d before calving were divided into two groups and fed diets containing moderate (12.7% CP, 36% rumen undegradable protein, (RUP) or high (14.7% CP, 40% RUP) protein. Higher prepartum CP diet increased milk production during the first 120 d in milk (DIM), but most of that effect was detected for the primigravid cows. Primigravid cows fed the prepartum diet higher in protein produced 2.0 kg/d more milk and 3.1 kg/d more 3.5% fat-corrected milk (FCM) during early lactation. Yields of milk fat and protein in early lactation were also increased by the high prepartum CP diet fed to primigravid cows. During the complete lactation, the response to prepartum dietary protein differed between primigravid and multiparous cows. Yields of milk, 3.5% FCM, and milk fat and protein were not affected by the prepartum diet for primigravid cows, but decreased for multiparous cows fed the high protein diet. However, primigravid cows fed the high prepartum protein diet had a higher 305-d mature equivalent milk yield. Colostrum composition, blood metabolites, ovarian activity, and disease incidence were not influenced by prepartum protein. Data from this study suggest that the current prepartum protein recommendation seems to be adequate for multiparous cows, but late-gestation primigravid cows might benefit from diets with a CP content above 12.7%.

Evaluation of periparturient dairy cows and contact surfaces as a reservoir of Cryptosporidium parvum for calfhood infection.

OBJECTIVE: To determine whether periparturient cows or contact surfaces to which newborn calves are exposed are reservoirs of Cryptosporidium parvum oocysts. ANIMALS: Periparturient cows and their calves. PROCEDURE: Using direct fluorescent antibody (DFA) and acid-fast (AF) assays, fecal samples taken before and after calving from periparturient cows were tested for C parvum oocysts. Fecal samples from calves were collected every other day from age 7 to 21 days and were tested by use of the AF assay. Topsoil from close-up and maternity pens and scrapings from wooden walls and floors of calf hutches were tested for C parvum oocysts by use of DFA assay. RESULTS: None of the 384 fecal samples obtained 1 to 21 days before or after calving or on the day of calving from 154 periparturient cows contained detectable C parvum oocysts. Despite this lack of detectable periparturient shedding, the period prevalence of calfhood infection was 92% (123/134) from age 7 to 21 days. Soil samples from the close-up and maternity pens where newborn calves spend the first 12 hours of life also were negative for C parvum oocysts. Wood scrap ings from the outer 2 mm of the walls and floors of empty and cleaned calf hutches that were ready to receive calves were C parvum oocyst-positive. CONCLUSIONS: Conditional on sensitivity of DFA, periparturient cows did not appear to shed detectable C parvum oocysts. In contrast, the floors and walls of wooden calf hutches contained detectable C parvum oocysts on the surface.

Field trials of an oral calcium propionate paste as an aid to prevent milk fever in periparturient dairy cows.

Trials were conducted to test the efficacy of a calcium propionate paste as an aid to prevent milk fever and to improve the health of dairy cows. Each calcium propionate treatment tube supplied 37 g of calcium. In trials involving Holstein herds and a Jersey herd, two (trials 1 and 2) or three (trial 3) calcium propionate tubes were given at calving and again at 12 h after calving. For the Jersey herd, calcium propionate treatment (two tubes) reduced the incidence of milk fever from 50% in control cows to 29% in treated cows. Plasma obtained 24 h after calving from treated cows had higher calcium, lower NEFA, and lower beta-hydroxybutyrate concentrations than did plasma from control cows. No other benefits of calcium propionate treatment were significant for health or for productivity of the cows. Calcium propionate treatment had no significant effects on blood calcium, NEFA, or beta-hydroxybutyrate in the Holstein herds studied. However, calcium propionate did reduce the number of cows with subclinical hypocalcemia (< or = 7.5 mg/dl of plasma calcium) at 24 h after calving in both trials involving Holstein cows. Calcium propionate treatment was beneficial in reducing subclinical hypocalcemia in all trials and reduced the incidence of milk fever in a herd having a problem with milk fever.