Moderate overfeeding of different sources of metabolizable energy and protein. II: Effects on inflammatory status of sheep in late pregnancy and growth trajectory of the offspring.

Our objective was to evaluate the effects of moderate overfeeding of different sources of metabolizable energy (ME) and protein (MP) on inflammatory status of sheep in late gestation and short-term growth performance of the offspring. A total of 32 healthy pregnant Zell ewes (2.5 ± 1 years old, 42.19 ± 1.65 kg body weight [BW]) were selected 7 weeks before lambing. After receiving a ten-day adaptation diet, eight ewes were randomly allocated to each of the four treatments including: 1) The adaptation diet that fulfills ME and MP requirements, according to the National Research Council's (NRC, 2007) recommendations for late pregnant ewes (CON); 2) A diet with 10% higher levels of ME than CON, using corn grain for extra ME (HEC); 3) A diet with 10% higher level of ME compared to CON, using flaxseed for additional ME (HEF); and 4) A diet with a 10% higher level of MP than CON, using a rumen-protected lysin and methionine supplement (RP-Lys & Met) to supply extra MP (PRO). After lambing, ewes continued their dietary treatments until 30 days postpartum; however, the content of ingredients were proportionally increased to meet the recommended levels of energy and protein for lactating ewes (NRC, 2007). Blood samples from the ewes were taken on days -21, -14, and -7 before parturition. Colostrum yield and components were determined, and lamb's BW and milk intake (MI) were measured weekly until 28 days of age. Other growth performance indexes were computed accordingly. Blood samples from the offspring were taken on days 15 and 30 of life. The data was analyzed using SAS software (SAS Institute Inc., 9.4). Compared with the CON, HEF-fed ewes were the only group that had lower levels of oxidative stress and blood inflammatory markers at -7 d before parturition (P < 0.05). Concentrations of aminotransferases in CON-fed ewes were greater than other groups in late gestation (P ≤ 0.05). Offspring of HEF- and PRO-fed ewes had higher birth BW than lambs of the CON-fed group (3.71 and 4.11 vs. 3.01 ± 0.24, Kg for HEF, PRO, and CON, respectively). Except for week 2, lambs of CON-fed ewes had lower BW gain compared with the other offspring (P < 0.01). Lambs of PRO-fed ewes had greater levels of plasma immunoglobulin G (IgG, days 15 and 30 of life; P < 0.05) and MI (from week 2; P < 0.001) than other groups. In conclusion, regardless of the source, moderate overfeeding of ME/MP was more beneficial for the immune status of late pregnant dams and the offspring's performance than non-overfed ones.

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.

Physically effectiveness of beet pulp-based diets in dairy cows as assessed by responses of feed intake, digestibility, chewing activity and milk production.

Nine multiparous Holstein cows (DIM = 56 ± 5 day) were randomly assigned to three experimental diets containing fine-dried (T1), normal-dried (T2) and pelleted (T3) beet pulp (BP) at 12% on a dry matter basis in a 3 × 3 change over design in three 21 day periods to evaluate the effects of three types of BP. Bulk density, functional specific gravity and water-holding capacity of ration and intake were similar, but intake of physically effective fibre was different among treatments. Without significant differences, nutrients' digestibility in T1 trended to be higher than T2 and T3. Ruminal liquid pH and N-NH3 concentration were lower in T1 and higher in T3 than T2. Grinding and pelleting of BP increased and decreased volatile fatty acid concentration respectively. Grinding decreased acetate and propionate and increased butyrate and lactic acid. In contrary to pelleting, grinding of BP increased the particulate ruminal passage rate, but decreased ruminal mean retention time and lower compartment mean retention time. Pelleting of BP decreased ruminal passage rate, but increased ruminal mean retention time and lower compartment mean retention time. Grinding increased 5.64, 5.9 and 5.8% eating time, rumination and total chewing activity in comparison with normal BP respectively. Pelleting increased 2.7%, 16.3% and 10.0% eating time, rumination and total chewing activity in comparison with T2 respectively. Milk yield had no significant difference, but milk yield adjusted to 4% fat, and milk fat (kg/day), fat, protein, casein and total solid of milk (%) were affected by the treatments. Results from this experiment show that based on milk fat assay, grinding did not reduce effectiveness of BP, but pelleting significantly increased effectiveness of BP. In addition, based on total chewing activity, grinding did not reduce physically effectiveness of BP, but pelleting of BP increased its physically effectiveness.

Grain source and marginal changes in forage particle size modulate digestive processes and nutrient intake of dairy cows.

This study investigated the effects of, and interactions between, dietary grain source and marginal changes in alfalfa hay (AH) particle size (PS) on digestive processes of dairy cows. A total of eight Holstein dairy cows (175 days in milk) were allocated in a replicated 4 × 4 Latin square design with four 21-day periods. The experiment was a 2 × 2 factorial arrangement with two levels of theoretical PS of AH (fine = 15 mm or long = 30 mm) each combined with two different sources of cereal grains (barley grain alone or barley plus corn grain in a 50 : 50 ratio). Results showed that cows consuming diets supplemented with corn had greater dry matter and nutrient intakes (P < 0.01), independent of forage PS. In addition, the apparent digestibility of fiber fractions was greater for diets supplemented with corn (P = 0.01). The feeding of barley grain-based diets was associated with greater apparent digestibility of non-fiber carbohydrates, and this variable was even greater when long AH was fed (P = 0.04). Moreover, the feeding of long AH resulted in longer time spent eating (P = 0.03) and higher pH (P < 0.01), as well as a tendency for higher acetate-to-propionate ratio in the rumen fluid (P = 0.06) at 3 h post feeding. In conclusion, the results indicated that the marginal increase of PS of AH may prolong eating time and improve rumen fermentation, particularly in diets based on barley grain. Partial substitution of barley grain by corn can improve feed intake and fiber digestibility in mid-lactation dairy cows.