Differential average daily gain of pregnant Holstein × Gyr dairy heifers causes placental adaptations to support fetal growth and development.

This study aimed to evaluate the effects of differential average daily gain targets of dairy heifers throughout gestation on placental hemodynamics, uterine involution, colostrum production of the heifers, and effects on newborn calf weight and immunity transfer. Fourteen Holstein × Gyr heifers with an average body weight of 446 ± 46.7 kg and age of 25 ± 3.9 mo were randomly assigned to the following treatments: moderate body weight gain (MOD, n = 7), where heifers were fed to achieve 0.50 kg/d; and high body weight gain (HIG, n = 7), where heifers were fed to achieve 0.75 kg/d. Target average daily gains were established based on common tropical dairy production systems. The heifers received a total mixed ration feed twice daily starting at 70 d of gestation. Placentome vascularization was assessed using a color Doppler ultrasound at 180, 210, and 240 d of gestation. After calving, cotyledons were counted and sampled to analyze the mRNA expression of placental angiogenesis markers. After birth, calves were weighed and fed colostrum, and transfer of passive immunity efficiency was assessed. A significant increase in cotyledons was detected for MOD placenta soon after expulsion (81.5 ± 12.91 vs. 63.6 ± 10.52). Placentome vascularization at the final third of gestation increased for MOD heifers compared with HIG. Greater mRNA expression after membrane expulsion of VEGFB and IGFR1 in cotyledons and a greater estradiol concentration in circulation 1 d before calving was found for MOD heifers compared with HIG heifers; however, uterine involution postpartum was not different between treatment groups. Greater colostrum production was observed in HIG heifers (3.9 ± 1.05 vs. 2.2 ± 1.57 L) but with lower quality (25.2 ± 0.51 vs. 29.5 ± 0.65 Brix). No differences were observed in birth weight or transfer of passive immunity efficiency between treatments; however, HIG calves had significantly greater vitality scores than MOD calves. The results of this study indicate that a moderate feeding regimen enhances placental blood flow by increasing angiogenesis, which suggests improved nutrient transfer to the fetus without major effects on its development during the neonatal stage, colostrum production, or uterine involution in the heifers.

Unveiling unstable non-acid incidence in Holstein cows fed with corn silage or sugarcane.

We aimed to evaluate the incidence of unstable non-acid milk (UNAM) in cows fed either sugarcane or corn silage. Second, we aimed to evaluate the effect of daily variation (d 1 to 4) and alcohol grades (72, 78, and 80%) on UNAM incidence. The experiment was conducted as a split-plot crossover design, with 2 periods and 2 roughage types (sugarcane or corn silage). Thirteen multiparous Holstein cows with an average of 281 ± 29 d in milk were randomly distributed into 2 diets. Individual blood (analysis of total proteins, albumin, urea, calcium, phosphorus, magnesium, iron, chloride, glucose, and lactate) and milk samples (analysis of protein, fat, lactose and total solids, somatic cell count, and characterization of the protein profile) were collected during the last 4 d of each period. For UNAM identification, the alcohol test was conducted in milk samples at 4°C; specifically, if the sample presented the formation of clots, this would be noted as positive for UNAM. In addition, the Dornic acidity analysis was performed in the same samples to evaluate the true milk acidity. The use of sugarcane and higher degrees of alcohol were associated with increased UNAM. We observed no daily variation in UNAM. Nevertheless, we found no roughage type effect on the variables most commonly associated with UNAM, such as changes in salts in the casein micelle and, consequently, the zeta potential and the κ-casein (CN) fraction. The Pearson correlation analysis showed that the zeta potential and the concentrations of αS2-CN, blood ionic calcium, lactate, and glucose increased as the incidence of UNAM increased, showing a positive correlation among these variables. In contrast, the concentrations of lactose, phosphorus, and potassium decreased as UNAM increased, presenting a negative correlation. This study brought important discoveries to unveil why cows manifest UNAM. For instance, higher alcohol grades and cows fed with sugarcane had increased the incidence of UNAM. Additionally, animals with a higher incidence of UNAM (sugarcane-fed cows) were related to increased ionic calcium and glucose and changes in milk protein profile, with lower levels of BSA, ß-CN, and α-lactalbumin and greater αS1-CN content, all of which were correlated with UNAM. Nonetheless, this trial also provides evidence for the need for further studies to better understand the physiological mechanisms that directly affect the stability of milk protein.

Performance and feeding behavior of Holstein and Holstein × Gyr crossbred heifers grazing temperate forages.

This study aimed to investigate the difference between Holstein and Holstein × Gyr breeds on feeding behavior and performance of heifers grazing temperate pasture. The experiment was carried out in 89 days, split into 14 days of adaptation, and 3 periods of 25 days. Two treatments were used: Holstein (HOL; n = 7) and Holstein × Gyr (HG; n = 7). Heifers grazed a consortium of ryegrass and bristle oats and were supplemented individually daily with cornmeal at 0.33% of body weight plus 5 kg/day of corn silage. For 3 consecutive days, feeding behavior was observed for individual animals from direct visual observation recording at 10-min intervals. The digestibility trial was performed on day (d) 16 to d24 of each period. Body measurements and weight were taken at d0 and at d23, 24, and 25 of each period. Grazing duration, grazing frequency, and bite rate were greater for HOL than those for HG. Rumination characteristics, intake, digestibility, and body measurements were not affected by breed. Breeds had differences in grazing characteristics, but they did not influence performance or intake parameters. Therefore, HOL and HG heifers managed under temperate pasture in tropical countries have similar performances.

Body composition changes of crossbred Holstein × Gyr cows and conceptus during pregnancy.

This study aimed to evaluate the effects of plane of nutrition and advancing days of pregnancy (DP) on maternal body composition and fetal development. Differing planes of nutrition were established by 2 feeding regimens (FR): ad libitum (AL) or maintenance (MA). Sixty-two nonlactating multiparous Holstein × Gyr cows with average body weight of 480 ± 10.1 kg and an age of 5 ± 0.5 yr were used. Cows were divided into 3 groups: pregnant (n = 44), nonpregnant (n = 12), and baseline reference cows (n = 6). The 56 pregnant and nonpregnant cows were randomly allocated into 2 different FR: AL or MA. Cows fed at MA received 1.15% of their body weight on a dry matter (DM) basis, receiving corn silage and a concentrate-based diet at a ratio of 93:7 on a DM basis. Reference group cows were slaughtered at the beginning of the experimental period to estimate body composition and empty body weight. To evaluate the effects of DP, pregnant and nonpregnant animals were slaughtered at d 140, 200, 240, and 270 of gestation. Feeding regimen affected maternal tissue composition. Days of pregnancy affected fresh weight (FW), DM, and energy content, but no differences were observed for crude protein (CP) and ether extract (EE) because of DP. Feeding regimen affected mammary gland components (CP, EE, and energy content), but not fresh or dry weights. Days of pregnancy influenced almost all mammary gland components except energy content. Regarding the uterus, FR affected only fresh and dry weights; however, DP affected every uterus component measured. The only interaction between FR and DP in this study was observed for placental FW. Cows fed AL on d 270 presented the same placental FW as cows at MA and AL on d 200 and 240. Further, pregnant cows fed at MA on d 270 had greater placental FW than cows fed AL at this day. Days of pregnancy, but not FR, influenced the composition of fetal fluids in pregnant cows. Finally, cows fed at MA had greater FW for the fetus than cows fed AL; however, fetus composition changed over DP. The FW, DM, EE, and energy content increased until d 270, but CP decreased. In conclusion, the novelty of our data presents how changes due to FR and DP occur in maternal tissues and the conceptus.

Supplementation strategies affect the feed intake and performance of grazing replacement heifers.

The literature lacks studies investigating the performance of supplemented replacement heifers grazing on intensively managed warm-season pasture. Our objective was to evaluate the effects of supplement composition (energetic or protein) on the performance, muscle development, thermogenisis, nutrient intake, and digestibility of replacement Holstein heifers grazing Mombaça grass. Eighteen Holstein heifers with an average age and initial body weight (BW) of 12.57 ± 2.54 mo and 218.76 ±47.6 kg, respectively, were submitted to a randomized block design, with six replicates on a rotational grazing system of Panicum maximum cv. Mombaça pasture. Treatments were: control (CON; mineral salt ad libitum); energy supplement (ENE; corn meal as supplement, 8% CP and 3.78 Mcal/kg DE); and protein supplement (PRO; corn and soybean meal, 25% CP and 3.66 Mcal/kg DE). Supplements were individually fed at 0.5% BW. The experiment lasted 120 days, subdivided into three periods. Titanium dioxide and indigestible neutral detergent fiber (iNDF) were used to estimate the intakes and digestibility of the nutrients. BW, wither height, thoracic circumference, body length, and ultrasound of ribeye fat thickness measurements were taken once per period. Body condition score (BCS) was assessed twice during the experiment. The MIXED procedure of SAS, including period as a repeated measure, was used and significance was declared at P ≤ 0.05. Dry matter intake (DMI), CP intake (CPI) and DE intake were greater in heifers fed PRO compared to CON and ENE. Heifers supplemented with ENE had the lowest DMI. Treatment affected pasture intake/BW; it was similar between PRO and CON heifers, and lower for the ENE treatment. A treatment × period interaction was observed for NDF intake (%BW), in which heifers fed PRO and CON had the greatest NDF intake and ENE had the lowest. The digestibility of DM was the greatest in PRO-supplemented heifers and the lowest in CON heifers. Heifers fed ENE had decreased CP digestibility compared to PRO and CON heifers. Average daily gain (ADG) and thoracic circumference gain were greatest in the PRO treatment. BCS was greater in PRO compared to CON and ENE heifers. Supplementing Holstein heifers at 0.5% BW using PRO supplementation resulted in better animal performance, primarily greater ADG, than feeding ENE or not supplementing (CON). In conclusion, our results indicate that dairy heifers should be fed a protein supplement when grazing intensively managed Mombaça grass pasture.

Effect of selected feed additives to improve growth and health of dairy calves.

The aim was to evaluate the effect of different feed additives on intake, performance, and fecal consistency index (FCI) of dairy calves from 6-60 d of age and its residual effect 15 d after weaning. Fifty Holstein calves (38 ± 1.0 kg BW) were fed 5 L/d of milk plus starter feed until weaning, and corn silage and concentrate after weaning. The treatments were: control (CON), monensin (MON; 30 mg/kg of starter), probiotic E. faecium (PROB; 70 mg/kg of starter), essential oils (EO; 300 mg/kg of starter), or PROB + EO (EOPROB). Fecal score and dry matter intake (DMI) were measured daily, and animals were weighed every 15 d. A DNA extraction from feces was performed to identify the presence of microorganisms (E. coli, Hafnia, Shiguella, Lactobacillus spp, Enterococcus spp, and Enterococcus faecium NCIMB 10415) by PCR. Two 72-h digestibility trials were performed at days 20-28 and 50-56, by total fecal collection. The DMI before weaning was greater for EO (903.0 g/d) compared with MON (794.3 g/d) and EOPROB (783.1 g/d). The FCI decreased during pre-weaning for EO and MON. Average daily gain (ADG) and feed efficiency (FE) did not differ among treatments before weaning. After weaning, DMI and FCI did not differ among treatments. The EO had greater ADG (917.5 g/d) compared with CON (615.8 g/d) and PROB (592.6 g/d). The FE improved with EO (0.72 g/g) over CON (0.36 g/g), MON (0.49 g/g), and PROB (0.36 g/g). The PCR results showed absence of E. faecium NCIMB 10415 in animals fed PROB and CON. Animals fed PROB had greater intake of CP and NDF than animals fed EOPROB. The EO can be added to the dairy calf ration to improve fecal score and increase DMI. The pre-weaning FCI decrease with MON and increase with PROB.