Effects of energy density in close-up diets and postpartum supplementation of extruded full-fat soybean on lactation performance and metabolic and hormonal status of dairy cows

Extruded Full-Fat Soybean

Effects of energy density in close-up diets and postpartum supplementation of extruded full-fat soybean on lactation performance and metabolic and hormonal status of dairy cows

INTRODUCTION:

About 75% of diseases in dairy cows occur within the first month after calving. Therefore, the transition period from pregnancy to lactation is a metabolically sensitive phase. Due to increased energy demands after calving and insufficient intake through feed, cows experience negative energy balance. To prevent this, appropriate strategies must be implemented to avoid excessive mobilization of body fat. Previously, this strategy involved reducing the use of low-quality forages.

Extruded soybean full-fat (ESB) is used in the diet of high-producing dairy cows because it provides suitable energy and protein. Additionally, this feed allows for greater release of amino acids in the intestine, enabling increased milk and milk protein production. However, few studies have investigated the use of ESB and its metabolic responses after calving.

Goals:

This article examined the effect of energy density during the close-up period and the use of extruded soybean full-fat (ESB) after calving on intake, body weight, metabolic status, and performance of dairy cows.

MATERIALS AND METHODS:

This study was conducted based on the hypothesis that simultaneous feeding of extruded soybean full-fat (ESB) with a low-energy diet could improve the metabolic status of the animals. To this end, 60 multiparous Chinese Holstein cows, 60 days before calving (dry period) and 56 days postpartum, with similar body weight, parity, and 305-day milk production, were evaluated. The cows were moved to the tie-stall barn 21 days before calving (close-up period). Then, they were assigned to one of three dietary treatments until calving: Low energy density diet (LED) with 88% of required NEL (NEL = 1.25 Mcal/kg DM), Medium energy density diet (MED) with 120% of required NEL (NEL = 1.41 Mcal/kg DM), High energy density diet (HED) with 157% of required NEL (NEL = 1.55 Mcal/kg DM). After calving, cows were assigned to either a control group (CON; crude protein = 17.01% DM, NEL = 1.60) or a treatment group (TRT; crude protein = 18.57% DM, NEL = 1.66) receiving 1.5 kg per day of ESB (7.2% of total DM intake) containing 38.7% crude protein and 20.6% ether extract. The cows were evaluated based on physical performance, production performance, and blood metabolites and hormones.

RESULTS AND DISCUSSION:

Before calving:

Daily dry matter intake (DMI) before calving was affected by treatments as follows: LED treatment: 9.84 kg/day MED treatment: 11.88 kg/day HED treatment: 14.32 kg/day In this study, to reduce dietary energy density, corn residue from the farm was used in the rations. Therefore, cows fed the LED diet consumed higher NDF content but lower DMI. Regarding the percentage of NEL (Net Energy for Lactation) requirements met before calving, cows fed the LED diet lost 0.05 units of body condition score (BCS), whereas cows in the MED and HED treatments increased their BCS by 0.04 and 0.12 units, respectively.

Cows fed the HED diet had higher blood glucose and insulin levels compared to the LED group, due to greater intake of rapidly fermentable starch and increased propionate production as a precursor for gluconeogenesis. Cows on the LED diet had non-esterified fatty acid (NEFA) concentrations of 0.3 milliequivalents per liter, which exceeded the allowable threshold. Therefore, they were at a higher risk of developing metritis and retained placenta. Due to higher energy intake in the MED and HED groups, less fat mobilization occurred, resulting in lower NEFA production. However, these two treatments had higher levels of beta-hydroxybutyrate (BHBA). Leptin, an important hormone related to hyperphagia, DMI, energy balance, and insulin concentration, did not differ among the treatments. The lack of leptin differences despite variations in DMI, energy balance, and insulin levels contradicts previous studies. This may be due to the genetic background of the Chinese Holstein cows used in this experiment, as genetics have been reported to significantly influence circulating leptin concentrations.

After calving:

There was no interaction between the pre-calving treatments and the post-calving experimental treatments in terms of DMI, BCS, body weight, energy balance, cholesterol, BHBA, blood urea nitrogen (BUN), glucose, and triglycerides. After calving, cows fed with HED and MED lost more body weight and BCS compared to the LED treatment. Cows fed with LED began to gain body weight and BCS during weeks 5 to 8 of lactation. The loss of BCS after calving is influenced by BCS at calving, milk production, and milk fat production after calving. However, in this study, milk fat content and milk yield were not affected by the pre-calving treatments.

The use of extruded soybean (ESB) in the diet of fresh cows led to an increase in milk production by 6.4%, milk protein by 5.8%, milk lactose by 6.7%, and solids-not-fat in milk by 6.6%, although there was a tendency for a 5.7% decrease in milk fat during the first 4 weeks of lactation. However, no effect of ESB on production performance was observed from weeks 5 to 8. Previous studies reported that using 23.7% ESB (as a percentage of total dry matter) increased milk production during the first 8 weeks of lactation; using 12% ESB as a replacement for soybean meal increased fat-corrected milk (FCM) by 3.5%, about 5.1 kg per day in mid-lactation; and using 7% ESB in early lactation increased milk production. The increased milk production observed with ESB in the TRT group may be due to the higher energy density of the diet compared to the CON group. Additionally, increased availability of amino acids in the intestine could lead to more amino acids being delivered to the mammary tissue for milk synthesis. The reduction in milk fat associated with ESB in this study may be attributed to a dilution effect. Besides dilution, the decrease in milk fat from feeding ESB could be due to the fatty acid content in ESB. It has been reported that ESB, due to its C18:2 (linoleic acid) content, can be biohydrogenated in the rumen to C18:1 (oleic acid). The trans isomer of C18:1 can lead to a reduction in milk fat content.

[۱] hyperphagia

[۲] circulating leptin concentrations

Cows that were fed a low-energy density (LED) diet before calving and then assigned to the treatment group (TRT) had higher glucagon levels during the first 8 weeks postpartum compared to the control group (CON). This hormone can help prevent fatty liver disease by improving gluconeogenesis and increasing mRNA expression of gluconeogenic liver enzymes early in lactation. Therefore, the increase in glucagon after calving in cows fed a low-energy diet contributed to greater milk and lactose production.

An interaction effect between dietary energy density and ESB supplementation during the first 8 weeks of lactation was observed on NEFA, insulin, bilirubin, and globulin levels. The TRT treatment reduced NEFA and insulin levels in the MED and HED groups. The decrease in NEFA in the TRT group was not due to reduced fat mobilization, as there was no difference in BCS between TRT and CON groups, but rather due to increased NEFA utilization by the liver in the TRT group. In cows fed HED with ESB, bilirubin levels decreased, indicating improved liver function. For cows on the MED diet before calving, ESB supplementation lowered blood globulin concentrations during the first 8 weeks of lactation and was associated with reduced total protein in the first 4 weeks postpartum. Blood globulin can serve as an indicator of positive acute-phase protein synthesis triggered by cytokines in the liver, where higher globulin levels suggest more severe inflammation, impaired liver function, and more pronounced negative energy balance in the first month of lactation. Therefore, from a metabolic status and liver function perspective, ESB supplementation is beneficial for cows in early lactation, especially those fed MED and HED diets before calving.

CONCLUSIONS:

Feeding high-energy diets during the close-up period can cause metabolic disturbances in fresh cows through increased NEFA levels, greater body weight loss, and higher body condition score loss compared to cows fed lower and medium energy diets. The use of high-energy and high-protein feeds such as full-fat soybean can help compensate for these disturbances and improve the productive performance of the cows. Considering the interactive effects of full-fat soybean use after calving and energy density before calving, it can be concluded that feeding full-fat soybean to fresh cows improves liver metabolic status.

REFERENCES :

Doi: https://doi.org/۱۰.۳۱۶۸/jds.۲۰۱۴-۹۱۱۲

Zhang, Q., et al., Effects of energy density in close-up diets and postpartum supplementation of extruded full-fat soybean on lactation performance and metabolic and hormonal status of dairy cows. Journal of Dairy Science, ۲۰۱۵. ۹۸(۱۰): p. ۷۱۱۵-۷۱۳۰.