Effects of linseed oil and rumen undegradable protein:rumen degradable protein ratio on performance of Holstein dairy calves.

The present study evaluated the interaction effects of n-3 fatty acids (from linseed oil (LSO), 0 v. 2·5, % DM basis) with rumen undegradable:degradable protein (RUP:RDP) ratios (low ratio (LR) 27:73; high ratio (HR) 38:62 based on crude protein %) in dairy calves' starter diet. Forty-eight 3-d-old female Holstein dairy calves (41·5 kg of body weight (BW)) were allocated in a 2 × 2 factorial arrangements in the following treatments (n 12 calves/each): (1) no supplementation of LSO with LR (NLSO-LR); (2) no supplementation of LSO with HR (NLSO-HR); (3) supplementation of LSO with LR (LSO-LR) and (4) supplementation of LSO with HR (LSO-HR). The calves were weaned on day 53 of the experiment and remained in the study until day 73. Intake was not affected by LSO and RUP:RDP ratio. However, average daily gain (ADG) was improved with LSO supplementation. Feeding the HR diet increased ADG compared with the LR diet during the entire period. Final BW was greater in calves fed on the LSO than those fed the NLSO diet. Microbial protein production did not differ among treatments. Calves fed on LSO diets had greater feed efficiency than those which were not fed on LSO diets. The calves supplemented with LSO had greater wither and hip heights compared with the unsupplemented calves. The glucose, cholesterol, HDL and insulin concentrations increased in calves supplemented with LSO. In conclusion, the HR diet improved calves' performance post-weaning; however, LSO could enhance growth performance of dairy calves during the pre-weaning period.

Short- and long-term effects of postpartum oral bolus v. subcutaneous Ca supplements on blood metabolites and productivity of Holstein cows fed a prepartum anionic diet.

Little information is available regarding the calcium (Ca) dynamics and how its concentration is influenced following the Ca treatment (injection or bolus) after calving in dairy cows. To evaluate the short- and long-term effects of different sources of Ca supplement to animals fed anionic diets during the pre-partum period, 36 multiparous Holstein cows were randomly assigned to 1 of 3 treatments: (1) control group without Ca supplement (CON); (2) subcutaneous injection of 500 ml of 40% w/v Ca borogluconate immediately post-calving (SUB) and (3) oral supplement of Ca bolus containing 45 g Ca immediately and 24 h post-calving (BOL). Serum concentrations of Ca, P and Mg were measured. Serum concentration of Ca was affected by treatments at 48 h of post-calving (P < 0.01). The mean Ca at 6 h was greater in SUB compared to CON group (2.34 v. 2.01 mmol/l; P < 0.002). The lowest Ca concentration at 12 h was related to CON cows compared with BOL and SUB cows (1.90, 2.16 and 2.14 mmol/l, respectively; P < 0.02); a similar trend was observed 24 h post-calving (P < 0.02). Serum concentrations of P and Mg were not influenced by treatments. Yield of milk, milk protein and fat-corrected milk were lowest (P < 0.05) in SUB cows within 3 weeks of lactation in comparison with CON and BOL cows. However, milk yield and milk composition did not show any difference among treatments throughout the first 3 months post-calving. In general, under conditions of this experiment, Ca supplements to fresh cows as an oral bolus are recommended in comparison with subcutaneous injection.

Effect of oral calcium bolus administration on milk production, concentrations of minerals and metabolites in serum, early-lactation health status, and reproductive performance of Holstein dairy cows.

AIMS: To determine the effects of oral Ca bolus administration in the early postpartum period of cows on milk yield and composition, blood metabolites, early-lactation health status, and reproductive performance. METHODS: Multiparous Holstein dry cows (n=66) with a mean parity of 3.1 (SD 0.35) were fed a diet with a positive dietary cation-anion difference (DCAD) prior to calving. They were randomly assigned to receive no treatment (Control; n=33) or two oral Ca boluses (n=33, 45 g of Ca per bolus); one was administered immediately after calving (Day 0) and the second 24 hours (±30 minutes) later. Blood samples were collected at calving, and on Days 2 and 7 to determine concentrations in serum of Ca, P, Mg, glucose, non-esterified fatty acids (NEFA), and ß-hydroxybutyric acid (BHBA). Milk yield was recorded daily and milk composition was determined weekly from calving until 28 day postpartum. Health and outcomes were determined during the first 30 days postpartum and reproductive outcomes to 180 days postpartum. RESULTS: Mean milk yields and composition over the first month of lactation were similar between cows in the two treatment groups (p>0.1). Mean concentrations of Ca in serum were not different between treatment groups on Day 0, but were higher on Day 2 for cows that received oral Ca boluses (1.77 (SE 0.07)) compared with Control cows (1.54 (SE 0.08)) (p=0.04). Concentrations in serum of P, Mg, glucose, NEFA and ΒHBA did not differ between treatment groups on any day of measurement. Fewer cows that received oral Ca were diagnosed with hypocalcaemia (total concentrations of Ca in serum <1.5 mmol/L) by Day 2 (2/33; 6%) compared with Control cows (12/33; 36%) (p=0.01). There was no difference in the prevalence of other health outcomes between treatment groups. The proportion of cows conceiving to first insemination was greater in cows that received an oral Ca bolus (19/29; 65%) than Control cows (12/29; 41%) (p=0.01). CONCLUSIONS: Oral Ca bolus administration increased concentrations of Ca in serum on Day 2 postpartum, and increased first service conception rates, in cows fed a diet with a positive DCAD prior to calving compared to cows that received no oral Ca bolus supplementation. Because of the small number of cows used in this study, further studies in large-scale dairy farms should be carried out to confirm these findings.

Interactions between levels of heat-treated soybean meal and prilled fat on growth, rumen fermentation, and blood metabolites of Holstein calves.

This study evaluated the interaction of RUP and fat levels on growth, rumen fermentation, and blood metabolites of Holstein calves. Forty 3-d-old calves (20 females and 20 males) with a starting BW of 40.6 ± 2.8 kg were used in a completely randomized design with a 2 × 2 factorial arrangement of treatments. Within sex treatments were: (1) high RUP and low fat (HRUP-LF); (2) low RUP and high fat (LRUP-HF); (3) high RUP and low fat (HRUP-LF); and high RUP and high fat (HRUP-HF). Low-RUP starter contained 21.5%, whereas high RUP starter contained 34.3% RUP as % of CP, whereas low fat starter contained 2.9% and high starter contained 5.8% crude fat based on DM. Isonitrogenous levels in the starter grain were maintained by replacing solvent soybean meal with heat treated soybean meal while fat levels were increased by the addition of prilled fatty acids. Calves were housed individually and had ad libitum access to water and calf starter throughout the study. All calves were weaned on d 60 of age but remained in the study until d 70 for final measurements. Overall, there was no interaction between RUP and fat levels for measured variables. Starter intake tended ( = 0.09) to be greater for calves fed low fat starter during the postweaning period, although over the whole experiment and during the preweaning period, differences in starter intake were not different. Although there were no differences for most VFA concentrations, the molar proportion of butyrate tended ( < 0.08) to be greater in the rumen of calves fed low-fat starter compared to those fed high-fat starter. Serum total protein was lower ( < 0.05) and serum cholesterol was greater ( < 0.01) for calves fed high-fat starter by d 65 of life. The concentration of alanine aminotransferase was also lower ( < 0.05) for calves fed high-fat starter compared to those fed low-fat starter on d 65, and these levels tended to increase with the addition of RUP ( < 0.07). In conclusion, no effects were attributable to feeding a high-RUP starter. However, feeding a calf starter with over 3% fat appeared to decrease starter intake as growth progressed.

Effects of alfalfa hay and its physical form (chopped versus pelleted) on performance of Holstein calves.

Inclusion of forage and its physical form in starter may affect rumen development, average daily gain (ADG), and dry matter intake (DMI) of dairy calves. To evaluate the effects of forage and its physical form (chopped vs. pelleted) on growth of calves under a high milk feeding regimen, 32 Holstein calves (38.8±1.1kg) were assigned at birth to 1 of 3 treatments in a completely randomized block design. Dietary treatments (% of dry matter) were (1) 100% semi-texturized starter (CON); (2) 90% semi-texturized starter + 10% chopped alfalfa hay (mean particle size=5.4mm) as a total mixed ration (TMR; CH); and (3) 90% semi-texturized starter + 10% pelleted alfalfa (mean=5.8mm) hay as a TMR (PH). Data were subjected to mixed model analysis with contrasts used to evaluate effect of forage inclusion. Calves were weaned at 76 d of age and the experiment finished 2 wk after weaning. Individual milk and solid feed consumption were recorded daily. Solid feed consumption and ADG increased as age increased (effect of week), but neither forage inclusion nor physical form of forage affected these variables pre- or postweaning. Plasma urea N was affected by treatments such that the CON group had a lower concentration than forage-fed groups. Forage inclusion, but not physical form, resulted in increased total protein in plasma. Although days with elevated rectal temperature, fecal score, and general appearance were not affected by dietary treatments, calves fed alfalfa hay during the first month of life had fewer days with respiratory issues, regardless of physical form of hay. We concluded that provision of forage does have some beneficial effects in calves fed large amounts of milk replacer, but pelleted alfalfa hay did not result in any improvement in calf performance or health.

Effect of linseed feeding on blood metabolites, incidence of cystic follicles, and productive and reproductive performance in fresh Holstein dairy cows.

This study was done to investigate the effect of feeding linseed on blood metabolites, incidence of cystic follicles, resumption of postpartum ovarian cyclicity, pregnancy rate, milk production, and composition in fresh Holstein dairy cows. A total of 399 dairy cows were assigned randomly to 2 diets. Diets contained either protected palm oil (CON) or extruded linseed (LIN) and were fed from calving to d 40 postpartum. Ovaries of each cow were examined on d 10, 20, 30, and 40 after parturition (parturition=d 0) by transrectal ultrasonography to determine follicular development, ovarian disorders, and cyclicity. Blood samples were collected at 14-d intervals for 6 wk starting on the day of parturition to determine plasma concentrations of glucose, ß-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and blood urea N (BUN). Results showed plasma glucose concentration was affected by the diets and was greater in the LIN treatment, but BHBA, NEFA, and BUN concentrations were similar among treatments. Dietary treatments had no significant effect on milk production and composition except milk fat percentage that significantly decreased in cows fed LIN (3.55%) compared with those fed with CON (4.17%). Plasma progesterone concentrations were greater in LIN treatment than CON treatment (1.31±0.09 vs. 0.87±0.09) at early postpartum. The resumption of cyclicity and onset of estrus were influenced by treatments and reduced by 7 d in LIN treatment compared with CON treatment. Cows fed diets enriched in LIN fatty acids had a lesser incidence of cystic follicles. Treatments did not differ significantly in terms of the number of days open, number of services per pregnancy, and pregnancy rate. In conclusion, feeding linseed immediately after parturition decreased milk fat and incidence of cystic follicles, increased progesterone concentrations early postpartum, and caused earlier resumption of cyclicity but did not affect pregnancy rate.

Metabolic and productive response to ruminal protein degradability in early lactation cows fed untreated or xylose-treated soybean meal-based diets.

Effects of different dietary rumen undegradable (RUP) to degradable (RDP) protein ratios on ruminal nutrient degradation, feed intake, blood metabolites and milk production were determined in early lactation cows. Four multiparous (43 ± 5 days in milk) and four primiparous (40 ± 6 days in milk) tie-stall-housed Holstein cows were used in a duplicated 4 × 4 Latin square design with four 21-day periods. Each period had 14-day of adaptation and 7-day of sampling. Diets contained on a dry matter (DM) basis, 23.3% alfalfa hay, 20% corn silage and 56.7% concentrate. Cows were first offered alfalfa hay at 7:00, 15:00 and 23:00 hours, and 30 min after each alfalfa hay delivery were offered a mixture of corn silage and concentrate. Treatments were diets with RUP:RDP ratios of (i) 5.2:11.6 (control), (ii) 6.1:10.6, (iii) 7.1:9.5 and (iv) 8.1:8.5, on a dietary DM% basis. Different RUP:RDP ratios were obtained by partial and total replacement of untreated soybean meal (SBM) with xylose-treated SBM (XSBM). In situ study using three rumen-cannulated non-lactating cows showed that DM and crude protein (CP) of SBM had greater rapidly degradable fractions. The potentially degradable fractions were degraded more slowly in XSBM. Treatment cows produced greater milk, protein, lactose, solids-non-fat and total solids than control cows. Increasing RUP:RDP reduced blood urea linearly. Feed costs dropped at RUP:RDP ratios of 6.1:10.6 and 7.1:9.5, but not at 8.1:8.5, compared with the 5.2:11.6 ratio. Intake of DM and CP, rumen pH, blood glucose, albumin and total protein, faecal and urine pH, changes in body weight and body condition score, and milk lactose and solids-non-fat percentages did not differ among treatments. Results provide evidence that increasing dietary RUP:RDP ratio from 5.2:11.6 to 7.1:9.5 optimizes nitrogen metabolism and milk production and reduces feed costs in early lactation cows. Reduced blood urea suggests reprodutive benefits.