Short communication: Temporal effect of feeding potassium carbonate sesquihydrate on milk fat in lactating dairy cows fed a fat-depressing diet

Exploring the cause of reduced production responses to feeding corn dried distillers' grains in lactating dairy cows

An experiment was conducted to identify the factors that cause reduced production of cows fed a diet with high corn distiller's grains with solubles (DDGS). We hypothesized that the factors could be high S content in DDGS which may directly (S toxicity) or indirectly [dietary cation-anion difference (DCAD)] cause reduced production. We also hypothesized that high polyunsaturated fatty acids (PUFA) in DDGS could be another major factor. In a randomized complete block design, 60 lactating cows (15 primiparous and 45 multiparious; average ± SD at the beginning of the trial: milk yield, 44.0 ± 6.9 kg/d; DIM, 123 ± 50; BW, 672 ± 82 kg) were blocked and cows in each block were randomly assigned to one of the following treatments: SBM [4.7% fatty acids (FA), 0.22% S, and 178 mEq/kg DM of DCAD], a diet containing soybean meal as the main protein source; DG, SBM replacing mainly soybean byproducts and supplemental fat with DG at 30% dietary DM (4.7% FA, 0.44% S, and 42 mEq/kg DM of DCAD); SBM+S, SBM with sodium bisulfate for additional dietary S (4.8% FA, 0.37% S, and 198 mEq/kg DM of DCAD); SBM+CO, SBM with corn oil (4.7% FA, 0.23%, and 165 mEq/kg DM of DCAD); and DG+DCAD, DG with increased DCAD (4.7% FA, 0.40% S, and 330 mEq/kg DM of DCAD). Due to the limited tie stalls, the blocks of 1 to 6 started the experiment first as phase 1 and the rest of the blocks as phase 2 started the experiment after phase 1. All cows were fed the SBM diet for 10 d as a covariate period followed by the experimental period for 35 d. Data were analyzed using the PROC MIXED of SAS, block and phase were random effects and treatments, repeated wk, and interaction were fixed effects. There was an interaction of wk by treatment for DMI. While milk yield did not change, milk fat concentration tended to decrease (2.78 vs. 3.34%) for DG compared with SBM. Dry matter, OM, NDF, and CP digestibilities were lower when cows were fed the DG diet compared with SBM. Additionally, cows fed DG had lower blood concentrations of HCO3-, base excess, and tCO2 compared with SBM. The SBM+S diet did not affect production, nutrient digestibility, or blood parameters when compared with SBM. The SBM+CO diet decreased milk fat concentration and yield compared with SBM. The DG+DCAD diet tended to increase milk fat yield and concentration (1.24 vs. 1.47 kg/d; 2.78 vs. 3.37%) and increased ECM (40.9 vs. 45.1 kg/d) compared with DG but did not improve nutrient digestibility. However, blood HCO3-, base excess, and tCO2 were greater for DG+DCAD compared with DG. In conclusion, the indirect role of S-, altering DCAD, along with the high PUFA content in DDGS appears to be the factors causing reduced production responses to a high DDGS diet. Increasing DCAD to 300 mEq/kg DM in a high DDGS diet can be a feeding strategy to alleviate the reduced production responses.

Effect of dietary supplementation or cessation of magnesium-based alkalizers on milk fat output in dairy cows under milk fat depression conditions

We aimed to evaluate the effects of dietary supplementation with magnesium oxide and calcium-magnesium dolomite on milk fat synthesis and milk fatty acid profile or persistency in milk fat synthesis after their cessation in dairy cows under milk fat depression conditions. Twenty-four multiparous dairy cows in early lactation (mean ± standard deviation; 112 ± 14 d in milk) were used in a randomized complete block design. Milk fat depression was induced in all cows for 10 d by feeding a diet containing 35.2% starch, 28.7% neutral detergent fiber, and 4.8% total fatty acid (dry matter). The experiment was conducted in 2 periods. During the Mg-supplementation period (d 1-20), cows were randomly assigned to (1) the milk fat depression diet used during the induction phase (control; n = 8), (2) the control diet plus 0.4% magnesium oxide (MG; n = 8), or (3) the control diet plus 0.8% calcium-magnesium dolomite (CMC; n = 8). Compared with the control group, feeding the magnesium-supplemented diets increased milk fat concentration and yield by 12% within 4 d. During the 20-d Mg-supplementation period, both the MG and CMC diets increased milk fat concentration and yield, as well as 3.5% fat-corrected milk and energy-corrected milk yield, without affecting dry matter intake, milk yield, and milk protein and lactose concentrations. In the Mg-cessation period (d 21-30), all cows received the control diet, which resulted in a greater milk fat concentration and yield in the cows that had already received the MG and CMC diets in the Mg-supplementation period. Whereas, milk fat concentration and yield remained high after discontinuation of the magnesium-containing alkalizer until d 27. The difference in milk fat synthesis was associated with lower trans-10 C18:1 (-22%) and higher trans-11 C18:1 (+12.5%) concentrations in milk during the Mg-supplementation period. Furthermore, it was evident that within 2 d of supplementation, the trans-10:trans-11 ratio was lower in MG and CMC cows compared with cows receiving the control. This suggested that the effect of magnesium-based alkalizers on milk fat synthesis was mediated via a shift in ruminal biohydrogenation of cis-9,cis-12 C18:2 in the rumen. In conclusion, abrupt addition of magnesium oxide and calcium-magnesium dolomite increased milk fat synthesis, which persisted for 7 d after cessation of magnesium-based alkalizers. A similar ability to recover milk fat synthesis and normal fatty acid biohydrogenation pathways was observed for magnesium oxide and calcium-magnesium dolomite.

Effects of two new formulas of dietary buffers with a high buffering capacity containing Na or K on performance and metabolism of mid-lactation dairy cows

The present study was conducted to evaluate the effect of two new formulas of dietary buffers on intake, total tract digestibility, rumen pH, blood metabolites, and milk production of mid-lactation dairy cows. Nine multiparous cows (594 ± 46 kg BW; mean ± SD) averaging 120 ± 28 days in milk and producing 46.6 ± 3.4 kg/d were randomly assigned to a triplicate 3 × 3 Latin square. During each 21-d period, cows were offered one of three total mixed rations that varied in dietary buffer. The three types of dietary buffer were 1) 11.2 g/kg of dietary dry matter (DM) sodium bicarbonate (SB; control), 2) 8.7 g/kg of dietary DM high buffering capacity formula contained Na (HBNa), and 3) 7.4 g/kg of dietary DM high buffering capacity formula contained K (HBK). Each period was comprised of 14 d of dietary adaptation followed by 7 d of sampling. Measured buffering capacity was 102, 150 and 137 percent of NaHCO₃ for SB, HBNa and HBK, respectively. The amount of Na and K were 270 and 0, 310 and 0, and 250 and 60 g/kg for SB, HBNa, and HBK, respectively. Dry matter intake (DMI) tended (P = 0.06) to be lower with HBK (20.6 kg/d) than SB (21.0 kg/d) and HBNa (21.2 kg/d). No treatment effects were observed on rumen pH (averaged 5.88) and DM digestibility in the total digestive tract (averaged 79.4%). Yields of actual milk (38.1 kg/d) and 3.5% fat corrected milk (31.6 kg/d) were not affected by treatments, whereas yields of solid corrected milk (P = 0.07) and milk fat (P = 0.10) tended to be greater with HBK than SB and HBNa. Milk fat concentration in cows fed HBK was greater than in cows fed other treatments (32.5 vs. 29.5 and 29.6 g/kg; P = 0.04). Concentration of milk protein (32.2 vs. 30.6 g/kg) and lactose (46.8 vs. 44.4 g/kg) also were greater in cows fed HBK than those fed SB (P = 0.02). Efficiency of milk production was greater in cows fed HBK than SB (1.86 vs. 1.80; P = 0.01), whereas efficiency of solid corrected milk production was greater in HBK than SB and HBNa (1.64 vs. 1.51 and 151; P = 0.02). Blood concentration of Ca was higher with HBK compared with SB and HBNa (10.4 vs. 9.7 and 9.9 mg/dL, respectively; P = 0.01). These results indicated that under the current experimental condition, supplementation of dairy cow diet with a high buffering capacity buffer containing 60 g/kg K decreased DMI and improved milk composition and milk efficiency of mid-lactation dairy cows.

Can neutral dietary cation-anion difference (DCAD) decrease occurrence of clinical periparturient hypocalcaemia in dairy cattle?

BACKGROUND

Adjusting the dietary cation-anion difference (DCAD) is one of the most efficient ways to stimulate calcium homeostasis in periparturient dairy cattle. However, adjusting DCAD to the recommended negative values (-100 to -150 mEq/kg) is associated with decreased food intake and metabolic acidosis. The critical conditions of the animals at peripartum (i.e. drastic hormonal changes, decreased appetite and negative energy balance) can be detrimental to the health, productivity and welfare of the animals if combined with decreased feed intake caused by unpalatable acidogenic salts.

METHODS

In a cross-sectional study, we analysed the ration of eight small to large dairy herds with intensive husbandry systems, including 6949 dry cows. Sodium, potassium, chlorine and sulfur concentrations in the feed were determined and DCAD was calculated. The DCAD of the ration of the farms ranged from -33.5 to +24.7 mEq/kg. Parturient paresis (PP, or milk fever) prevalence was investigated and correlated to DCAD values.

RESULTS

Clinical PP occurrence in the dairies of this investigation on average declined by 87% (ranging from a 97% decline to 5% increase). This indicates that adjusting DCAD at neutral values (0 ± 30 mEq/kg range) may both lower the PP prevalence and increase ration palatability by lowering acidogenic salts in the ration.

CONCLUSIONS

Further research is recommended to investigate the effects of neutral DCAD on subclinical hypocalcaemia and food intake of the cattle.

Effects of spray-dried plasma protein product on early-lactation dairy cows

Spray-dried plasma protein (SDP) compared with blood meal (BM) may contain various functional and active components that may benefit animal health. The objective of this experiment was to investigate the effects of feeding SDP or BM on production and blood profile in dairy cows during the transition and early-lactation periods. Seventy-two Holstein cows at 14 d before calving were used in a randomized block design. During the prepartum period, cows were fed a typical late-gestation diet containing BM (100 g/cow per day; 100BM, n = 24) or SDP (100 g/cow per day; 100SDP; n = 48). After calving, cows that were fed BM prepartum were fed a typical lactation diet formulated to provide 100 g/d of BM (100BM). Half the cows that were fed 100SDP prepartum were fed a lactation diet formulated to provide 100 g/d of SDP (100SDP; n = 24), and half were fed a diet formulated to provide 400 g/d of SDP (400SDP; n = 24) on a dry matter basis where SDP replaced BM (100SDP) or BM and soybean products (400SDP). All diets were balanced for crude protein concentration and metabolizable protein supply assuming BM and SDP were equal in rumen-degradable protein and rumen-undegradable protein. All data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) as a randomized block design where contrasts were made for 100BM versus 100SDP for prepartum variables and 100BM versus 100SDP and 100SDP versus 400SDP for postpartum variables. Prepartum supplementation of SDP had no effect on plasma fatty acids and β-hydroxybutyrate (2 d before calving). Plasma fatty acids (255 ± 29 µEq/mL) and β-hydroxybutyrate (675 ± 70 µmol/L) at 8 and 14 d of lactation were not affected by SDP in the diet. Feeding SDP at 100 g/d compared with 100BM increased or tended to increase milk fat, protein, and lactose contents for 16 wk after parturition. Providing SDP at 400 g/d in the diet increased milk yield (42 vs. 39 kg/d), energy-corrected milk (44 vs. 41 kg/d), energy-corrected milk per kilogram of dry matter intake, and yields of milk fat (1.60 vs. 1.48 kg/d), protein (1.21 vs. 1.16 kg/d), and lactose compared with 100SDP. Body weight losses tended to be lower for 100SDP compared with 100BM without a difference between 100SDP and 400SDP. Plasma histidine concentration (d 14 of lactation) was lower for SDP compared with 100BM. In addition, plasma 1-methyl-l-histidine tended to be lower as inclusion rate of SDP increased. In conclusion, SDP at 400 g/d increased milk and milk component yields without an increase in feed intake. Studies evaluating effects of functional and active compounds in SDP on gut microbiome, gut health, and immune functions may be needed to determine mode of action.