Effect of amount of undegradable crude protein in the diets of high-yielding dairy cows on energy balance and reproduction

Patterns of blood biochemical parameters of peripartum dairy cows raised in either smallholder or semi-commercial dairy farms in Thailand

Background and Aim:

Data about dynamics of serum biochemical parameters and negative energy balance (NEB) related conditions differ among geographical areas or farm types. It should be cautious about applying those data to justify control and prevention strategies of NEB problems. Therefore, dynamics of blood biochemical parameters related to NEB condition of peripartum dairy cows raised in either smallholder (SH) or semi-commercial (SC) farms were studied.

Materials and Methods:

Thirty-two healthy pregnant dry cows were selected from five dairy farms in Western part of Thailand, including 15 and 17 cows from three SH and two SC farms, respectively. Blood samples were collected at 2 weeks before the expected calving date, and 1, 2, 4, and 8 weeks postpartum to determine concentrations of glucose, non-esterified fatty acid (NEFA), and b-hydroxybutyrate (BHBA). Body condition scores (BCSs) and milk yields were also recorded.

Results:

Dairy cows in both farm types suffered from NEB by elevation of serum NEFA and BHBA, and loss of BCS postpartum. Degrees of elevation in serum NEFA and BHBA were different between farm types. The SC cows showed more BCS loss postpartum, but lower serum NEFA. In the SH cows, even with less BCS loss, the cows showed high serum NEFA concentrations.

Conclusion:

Dairy cows in our study entered NEB condition even with low milk yields. Moreover, elevation of serum NEFA and BHBA postpartum was higher in our studied cows as compared with other studies in high producing cows of commercial dairy farms in temperate areas.

Effect of rumen degradable protein with or without fermentable carbohydrate supplementation on blood metabolites and embryo survival in cattle

High intakes of dietary protein, particularly rumen degradable protein (RDP), lead to elevations in systemic concentrations of ammonia and (or) urea and these may be increased further if associated with inadequate fermentable energy intake. High systemic concentrations of ammonia and urea have been associated with reduced reproductive performance in cattle. The objective of this study was to examine the effect of RDP and fermentable energy intake on a range of blood metabolites and on embryo survival in heifers. Oestrous synchronized, nulliparous beef heifers (no. = 162) were randomly assigned in a 2 ✕ 2 factorial designed experiment to two levels of RDP and two levels of fermentable energy. Grass silage-based diets were supplemented with either 0 (0U) or 240 (240U) g dietary urea (460 g/kg N) and these in turn with either 0 (0P) or 3 (3P) kg dry matter of molassed sugar-beet pulp pellets (MSBP) per day. The four treatments were, therefore, (1) 0U + 0P (no. = 43), (2) 0U + 3P (no. = 44), (3) 240U + 0P (no. = 40) (4) 240U + 3P (no. = 35), respectively. Systemic concentrations of ammonia, urea, insulin, glucose and progesterone were measured. Heifers were given artificial insemination (AI) and embryo survival measured by ultrasonography at 30 and again at 40 days after AI. Systemic ammonia and urea were elevated (P < 0·001) in the animals given the high RDP diets. Supplementation with MSBP reduced systemic urea in the heifers on both high and low RDP diets. Plasma ammonia concentrations were not affected by MSBP supplementation (P > 0·05). Plasma glucose was not affected by urea or MSBP treatment (P > 0·05) but was affected by day and time of sampling (P > 0·05). Plasma concentration of insulin was not affected by urea or MSBP supplementation or by day or time of sampling (P > 0·05). Plasma concentration of progesterone was not affected by diet or time of sampling (P > 0·05). The overall embryo survival rate was 62% and was not affected by dietary urea or fermentable carbohydrate or by systemic concentrations of ammonia, urea, glucose, insulin or progesterone (P > 0·05).

Effect of pasture crude protein and fermentable energy supplementation on blood metabolite and progesterone concentrations and on embryo survival in heifers

Seasonal milk production systems rely on heavy inputs of nitrogenous fertilizer, which typically generate pastures with a high crude protein (CP) and low fermentable energy concentration. High intake of CP, particularly in association with low rumen fermentable energy, increases systemic ammonia and urea and has been associated with reduced fertility in cattle. The objective of this study was to examine the relationship between pasture protein intake and fermentable energy supplementation on a range of blood metabolites and on embryo survival and development in cattle.

Oestrous synchronized, nulliparous beef heifers (no. = 175) were randomly assigned to one of four pasture-based dietary treatments in a 2✕2 factorial study carried out over 2 years. Animals were randomly allocated to either high (85 kg nitrogen (N) per ha; HN) or low (0·0 kg N per ha; LN) N fertilized pastures and within pasture treatment were randomly allocated to receive either zero or three (+3P) kg dry matter (DM) of molassed sugar-beet pulp (MSBP) per head per day as follows: (1) HN (no. = 44), (2) HN + 3P, (no. = 43), (3) LN (no. = 44), (4) LN + 3P (no. = 44). Blood samples were collected to measure systemic concentrations of ammonia, urea, insulin, glucose and progesterone. Heifers were artificially inseminated (AI) and pregnancy diagnosis was carried out by ultrasonography 30 days after AI. Subgroups of pregnant animals across treatments were slaughtered 40 days after AI to estimate conceptus development.

The HN pasture had a higher CP (P< 0·001) and lower water-soluble carbohydrate (P< 0·01) concentration. Plasma concentrations of ammonia (P< 0·05) and urea (P< 0·001) were higher in the animals on the HN pastures and were reduced (P< 0·05) by MSBP supplementation, but only in animals on the HN pastures. Embryo survival rate across treatments was high overall (71%) and not related to pasture CP concentration, fermentable energy supplementation or systemic concentrations of ammonia, urea, glucose or insulin. There was no relationship between dietary treatment or systemic metabolites and any of the estimates of conceptus development. Systemic insulin was not affected by pasture N treatment or MSBP supplementation (P> 0·05). Systemic concentrations of glucose were not affected by pasture N treatment (P> 0·05) but were increased by MSBP supplementation (P< 0·05). Systemic progesterone was not affected by pasture CP or MSBP supplementation (P> 0·05) but at day 7 after AI was positively related (P< 0·05) to embryo survival. Intake of high CP herbage elevated systemic ammonia and urea but there was no association with embryo survival rate or embryo development in heifers.

Starch digestion site : influence of ruminal and abomasal starch infusion on starch digestion and utilization in dairy cows

The effect of site of starch digestion on glucose metabolism in dairy cows was studied. Four multiparous Israeli-Holstein cows in mid lactation were used in a 4 × 4 Latin-square design. Average body weight of cows was 580 ± 38 kg, and average milk yield was 28 ± 3 kg/day. The cows were fitted with ruminal cannula and flexible T-cannulae in abomasum and ileum. Treatments were as follows : CON (control) : water was infused to the rumen. SR (starch-rumen) : 1.5 kg/day of maize starch solution was infused into the rumen. SA (starch-abomasum) : 1.5 kg/day of maize starch solution was infused into the abomasum. SCA (starch-casein-abomasum) : 500 g/day sodium caseinate and 1.5 kg/day of maize starch solution was infused into the abomasum. Total intake of dry matter (DM), was similar in all treatments and averaged 19.9 kg/day. Total non-structural carbohydrate (TNC) intake averaged in 6.8 kg/day. The average TNC digested in the rumen was 4.95 kg/day for CON and SR cows and 3.34 kg/day for the SA and the SCA cows. The average TNC digestion in the small intestine was 1.18 kg/day for CON and SR cows and 2.41 kg/day for the SA and SCA cows. TNC digestibility in the small intestine was highest for the SCA cows at 0.83 as compared with other treatments. Concentrations of plasma glucose and insulin were similar between treatments. No difference between treatments in total volatile fatty acid (VFA) concentration in ruminal fluids was observed. However, propionate proportion in total VFA was higher in the SR cows than in other treatments (P< 0.04). Milk yield and composition were not affected by treatments in the present study. It was concluded that the amount of dietary protein in the small intestine has a considerable effect on TNC digestibility. Under conditions of high milk production and high rumen-by-pass TNC flow, efficiency of TNC utilization might be greater since TNC is digested in the small intestine rather than in the rumen.

Impacts of the source and amount of crude protein on the intestinal supply of nitrogen fractions and performance of dairy cows

The objective of this article was to review and summarize the significance of the amount and source of dietary crude protein supplements on the supply of nitrogen fractions passing to the small intestine and the performance of lactating dairy cows. A meta-analysis was used to evaluate 2 data sets, one for nitrogen flow to the small intestine and one for performance of cows. The response of dairy cows to rumen-undegradable protein supplements is variable. A portion of this variable response from research trials is explained by the source of crude protein in the control diet, the proportion and source of rumen-undegradable protein in the experimental diet, the effect of rumen-undegradable protein on microbial protein outflow from the rumen, the degradability and amino acid content of the rumen-undegradable protein, and the crude protein percentage of the diet. Compared with soybean meal, the mean milk production responses to feeding rumen-undegradable protein supplements ranged from -2.5 to +2.75%. Because of the large variation and small magnitude of response when rumen-undegradable protein supplements are fed compared with soybean meal, efficiency of nitrogen utilization and the cost to benefit ratio for these crude protein supplements may determine the source and amount of crude protein to feed to dairy cows in the future.

Comparison of the German and the Dutch protein evaluation system in dairy nutrition when applied to different rations with graded protein levels

The Dutch (DVE) and the German (nXP) protein evaluation system were compared using data from four specially designed dairy feeding trials. The criterion for comparison was the divergence between predicted and observed milk protein yield with the respective protein evaluation system. Different forages were fed in each series of experiments, namely red clover/meadow grass, meadow grass, grass silage and maize silage, respectively. To achieve a diversified database, protein was supplied at 2 or 3 different levels in each experiment. Across all measured data, the two protein evaluation systems resulted sometimes in considerable differences between predicted and observed protein yield. The observed yield was overestimated by 223 g per cow and day with the DVE system and by 144 g per cow and day with the nXP system. The magnitude of the bias varied depending on the type of ration fed. In experiments with fresh forage the difference between predicted and observed milk protein yield was far greater with the DVE system than that calculated with the nXP system (difference 322 g vs. 162 g), whereas after feeding grass silage the differences between the two protein evaluation systems were small (194 g vs. 182 g). In experiments with maize silage the predicted value was close to the observed value both with the DVE and the nXP system (difference 48 g vs. 80 g).