Blood and hydrolyzed feather meals as sources of undegradable protein in high fat diets for cows in early lactation

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.

ADSA Foundation Scholar Award. Biology of dairy cows during the transition period: the final frontier?

The transition period, from 3 wk before to 3 wk after parturition, is critically important to health, production, and profitability of dairy cows. Most health disorders occur during this time. Compared with other stages of the lactation cycle, relatively little is known about fundamental biological processes during the transition period. The regulation and coordination of lipid metabolism among adipose tissue, liver, gut, and mammary gland are key components of the adaptations to lactation. Lipid accumulation in liver may contribute to health disorders and decreased milk production. Knowledge of key control points in hepatic metabolism of long-chain fatty acids is lacking, as is an understanding of the metabolic effects of hormones, growth factors, and cytokines that mediate stress. Recent evidence indicates that supplemental fats or restricted intakes before parturition can induce a coordinated set of metabolic changes in metabolism of long-chain fatty acids, including peroxisomal beta-oxidation, perhaps mediated by peroxisome proliferator-activated receptors. Estimates of the mixture of fuels constituting metabolizable energy in cows during the early postpartum period suggest that supply of amino acids and glucogenic compounds may be under proposed optima, whereas ketogenic and lipogenic compounds and long-chain fatty acids may be in excess. Because dietary fat does not suppress body lipid mobilization, during the early postpartum period supplemental fat may further imbalance the mixture of fuels and lead to decreased dry matter intake. Increased understanding of the biology of the transition period should decrease health problems and increase profitability of dairy cows.

Effects of rumen-undegradable protein on dairy cow performance: a 12-year literature review

In order to integrate and analyze knowledge on the use of protein supplements and protein nutrition of lactating dairy cows, we compiled a review of 108 studies published throughout the world, but principally in the Journal of Dairy Science between 1985 and 1997. In 29 comparisons from 15 metabolism trials, soybean meal was replaced by high amounts of rumen undegradable protein (RUP) as a supplement; the benefits were not consistently observed for flow to the duodenum, essential amino acids, or lysine and methionine. High RUP diets resulted in decreased microbial protein synthesis in 76% of the comparisons. However, fish meal provided a good balance of lysine and methionine when calculated as a percentage of total essential amino acids. In 127 comparisons from 88 lactation trials that were published from 1985 to 1997, researchers studied the effects of replacing soybean meal with high RUP sources, such as heated and chemically treated soybean meal, corn gluten meal, distillers grains, brewers grains, blood meal, meat and bone meal, feather meal, or blends of these sources; milk yield was significantly higher in only 17% of the comparisons. Fish meal and treated soybean meal accounted for most of the positive effects on milk yield from RUP; corn gluten meal resulted in mostly negative results. The percentage of fat in milk was depressed more by fish meal than by other RUP sources. Protein percentage was decreased in 28 comparisons and increased in only 6 comparisons, probably reflecting the decrease in microbial protein synthesis, as was observed for diets high in RUP. The data strongly suggest that increased RUP per se in dairy cow diets, which often results in a decrease in RDP and a change in absorbed AA profiles, does not consistently improve lactational performance.

Protein degradability and calcium salts of long-chain fatty acids in the diets of lactating dairy cows: productive responses

Our objective was to evaluate the effect of excessive intake of ruminally degradable crude protein [11.1 and 15.7% of dietary dry matter (DM)] and supplemental fat (Ca salts of long-chain fatty acids at 0 or 2.2% of dietary DM) on the productive performance of lactating Holstein cows (n = 45) during the first 120 d postpartum. The main N sources were soybean meal and urea in the diets with high concentrations of degradable protein versus a combination of vegetable and animal by-product feedstuffs in the diets with less degradable protein. Cows fed the diets with excess degradable protein had slower rates of increase in DM intake (DMI) and milk production, had lower plasma insulin and greater plasma glucose and urea concentrations, and lost more than twice the body weight of cows fed the diets with less degradable protein. Supplemental fat in the highly degradable protein diet reduced the loss of body condition, stimulated DMI, and reduced concentrations of plasma nonesterified fatty acids early postpartum compared with the highly degradable protein diet without added fat. Without affecting DMI, supplemental fat stimulated milk production (2 kg/d) starting at 3 wk postpartum. During early lactation, DMI and milk production were sensitive to the degree of ruminal degradability of protein and energy supplementation in the form of fat.

Influence of supplemental fats on reproductive tissues and performance of lactating cows

Fat supplementation (about 3% of dietary dry matter) has often positively influenced the reproductive status of the dairy cow, including increased size of the ovulatory follicle, increased numbers of ovarian follicles, increased plasma concentration of progesterone, reduced secretion of prostaglandin metabolite, increased lifespan of the corpus luteum, and improved fertility. Supplemental fat may allay partially negative energy status during the early postpartum period, yet often the positive reproductive influence of supplemental fat has been independent of the energy status of the cow. The fatty acid profile of supplemental fats is influential to their impact. Linoleic acid and eicosapentaenoic acid (found in fish meal) are proven inhibitors of cyclooxygenase in endometrial tissue of dairy cows. As a result, endometrial secretion of PGF alpha can be suppressed, thus potentially preventing early embryonic death. This process may be aided by the effect fat has in suppressing estradiol-17 beta secretion, thus reducing uterine PGF2 alpha secretion and decreasing the sensitivity of the corpus luteum to PGF2 alpha. Targeting of dietary fatty acids toward ovarian and uterine function may enhance efficiency of reproductive management and fertility.

Soybeans versus animal sources of rumen-undergradable protein and fat for early lactation dairy cows

Fifteen multiparous Holstein cows averaging 39 DIM were used in a replicated 5 x 5 Latin square design to compare roasted soybeans and animal by-products as supplements for increasing the RUP content of lactation diets based on alfalfa. The control diet contained roasted soybeans and was formulated to meet requirements for RUP. Rumen-undegradable protein in the diet was increased by including additional roasted soybeans or animal by-product proteins. To achieve diets with similar amounts of fat, we added tallow, hydrolyzed tallow fatty acids, or partially hydrogenated tallow to the control diet and to diets containing animal by-product proteins. Control diets and diets with high RUP were estimated to be 5.8 and 7.6% RUP (DM basis). The RDP of all diets was estimated to be approximately 11.3% of DM. Milk yield was increased by additional dietary RUP. Yield of FCM was greater for cows receiving animal byproducts than for those fed additional roasted soybeans. Cows fed additional RUP yielded more milk protein, but milk protein percentage was decreased. Milk fat percentage was reduced by additional dietary RUP, but fat yield was not affected. Nutrient digestibility was greatest for diets containing animal byproducts. Cows fed tallow yielded more milk, FCM, and protein that did those fed hydrolyzed tallow fatty acids or partially hydrogenated tallow. Lactation performance can be enhanced by supplementing animal by-products or roasted soybeans to diets based on alfalfa and formulated to meet NRC recommendations for RUP.

Effect of type of protein supplementation on duodenal amino acid flow and absorption in lactating dairy cows

Four multiparous lactating Holstein cows, fitted with cannulas in the rumen, duodenum, and ileum, were used in a trial with a 4 x 4 Latin square design to examine the effect of source and degradability of dietary CP supplements on AA flow and absorption in the small intestine. The CP supplements consisted of fish meal or meat meal as the animal by-products supplement and soybean meal or heated soybean meal as the plant by-products supplement. Fish meal and heated soybean meal constituted the high RUP diets, and meat meal and soybean meal constituted the low RUP diets. Dry matter intakes were similar among treatments. However, intakes of OM, rumen-degradable OM, total CP, and RDP were affected by the source of the CP supplement and were higher for diets with plant by-products than for those diets with animal by-products. Data were similar for the calculated in situ digestibilities and for true in vivo digestibilities of rumen-degradable OM. Efficiency of bacterial CP synthesis was similar among diets; however, nonbacterial CP flow to the duodenum and OM, CP, and disappearance of AA from the small intestine were affected by the interaction of supplement source and degradability. Heat treatment of soybean meal reduced the availability of most of the essential AA for absorption in the small intestine by 2.3% compared with that of soybean meal; the biggest such reduction (20%) occurred for Met. Availability of AA in the small intestine was affected by source and degradability of the CP dietary supplement. Heat treatment at 140 degrees C for 2.5 h reduced the availability of Met absorption from the small intestine. Although the differences among availabilities of the individual AA in the small intestine ranged from 80 to 84% among treatments, for high yielding cows, these differences may have practical significance.