Performing Department
Population Health
Non Technical Summary
Linseed expeller meal is a nutritional approach to increase the contribution of omega-3 FA in dairy calves. Omega-3 FA act as anti-inflammatory precursors reducing the likelihood of infectious diseases. Diarrhea and respiratory diseases are still common conditions affecting dairy calves, which result in undesirable morbidity and mortality rates, affecting the profit and genetic gain of dairy herds. The objective of the study is to compare the effect of linseed and canola expeller meal (25% DM of the starter) on weight gain, feed efficiency, incidence of diseases, and serum immunological metabolites in young female Holstein calves. The study will be conducted at the UGA dairy farm, Tifton, GA. A sample size of 16 female Holstein calves per group was calculated. Treatment group will be a starter with linseed expeller meal, and a control group with canola expeller meal. The starter will be weighed and offered ad-libitum from day 3. Calves will be weighed at birth, 28, and 56 d of age. A blood sample will be obtained at 7, 14, 21, 28, 35, 42, 49 and 56 d of age for serum collection. Haptoglobin, Interleukin-1 and 6, TNF-α, resolving-E1, protectin [CD59], and serological titers and interferon-gamma after vaccination against respiratory diseases will be assessed. The incidence of diarrhea and respiratory diseases will be also recorded. Average daily gain and feed efficiency will be statistically analyzed by ANOVA. Body weight, feed intakes, and serum metabolites will be analyzed by ANOVA for repeated measures. Diseases will be analyzed by logistic regression.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The objective of the present investigation is to compare the effect of linseed expeller meal and canola expeller meal as part of the concentrate (25% inclusion as DM basis) on average daily weight gain (ADG), concentrate intake, feed efficiency (FE), incidence and duration of digestive and respiratory disorders, concentrations of serum haptoglobin, TNF-α, interleukin-1, interleukin-6, resolvin-E1 and protectin (CD59), and immune responses to respiratory vaccines (interferon-gamma and antibody titers) in young female Holstein calves.
Project Methods
FarmThis study will be carried out at the UGA dairy (Tifton, GA) after approval of the UGA IACUC. The farm consists of 250 lactating Holstein cows housed in a free-stall system. Cows are milked 3 times a day and fed a total mixed ration based on corn silage, grass hay and concentrate. Dry cows are moved to a prepartum lot 30 d before expected parturition and give birth in the prepartum pen. After calving, the offspring is immediately separated from the dam and fed high quality colostrum (evaluated by a Brix refractometer, > 22%), within the first 4 h of life. Then, each calf is moved to individual plastic hutch bedded with sand. Calves are fed milk replacer (17% fat, 26% protein) twice a day (12.5% solids concentration) as follow: 2 liters AM and 2 liters PM during the first week of life; 3 liters AM and 3 liters PM from week 2 to 6; and only 3 liters AM from week 7 until week 8. After weaning, calves remained in their hutches until a minimum of 2.0 kg of starter is consumed. Beginning at 3 d of age, water and concentrate are offered for ad libitum consumption. Any health event is treated immediately, according to established standard protocols.Study DesignThis is a nutritional/clinical trial to be conducted under conventional settings of a Holstein dairy farm. In order to determine a difference of 150 μg/ml in the concentration of resolving E1 at 42 d of age between a group receiving linseed expeller meal (LIN) and a group receiving canola expeller meal (CAN), considering a SD = 100 μg/ml, 95% confidence, and 80% statistical power, a sample size of 16 female Holstein calves per group was calculated. The study is a Completely Randomized Design, where animals will be randomly allocated at the time of delivery. Eligible animals must be born from normal pregnant heifers, cows that experience a normal and standard dry period (45 to 70 d in length) and a normal parturition (no dystocia). Calves from LIN group will be fed a starter with an inclusion of 25% DM basis of linseed expeller meal. Calves from CAN group will receive a similar concentrate, but with canola expeller meal (25% DM basis) instead of linseed expeller meal. Both starters will be isonitrogenous and isoenergetic, but differed in their content of omega-3 and omega-6 FA. The diet will be formulated using the commercial ration formulator and evaluator software (NDS Professional, RUM&N, Reggio Emilia, Italy) based on the Cornell Net Carbohydrate and Protein System (CNCPS) version 6.55 (Van Amburgh et al., 2015). A daily gain of 0.82 kg/d plus a security margin of 10% will be considered. The starter will be prepared and mixed on the farm. The starter will be weighed and offered ad-libitum from day 3. Residual will be obtained the following day, weighed and replaced with fresh starter.Calves will be weighed at birth, 28 and 56 d of age. Starter intake will be measured daily from 5 to 60 d of age. Feed efficiency will be calculated as the amount of starter consumed (kg) to gain 1 kg of body weight.Blood sampling and lab analysesA blood sample from the jugular vein will be obtained at 7, 14, 21, 28, 35, 42, 49 and 56 d of age for serum collection at 8:00 AM before feeding the calves. Blood samples will be centrifuged at 3,000 g for 10 min. Serum will be separated and placed in plastic vials and stored at - 80 °C until analysis. Because there are several inflammatory and anti-inflammatory mediators participating in any inflammation process, key molecules have been selected as a reflex of an acute inflammatory process (haptoglobin), inflammation due to a response to an infection (Interleukin-1 and 6, TNF-α), and restoration of normal cellular function after an inflammation process (resolving-E1, and protectin [CD59], cytokines synthesized from omega-3 FA). A respiratory vaccine against BVD, IBR, PI3 and BRSV viruses will be administered at 35 d of age. Serum samples at day 35, 42, 49 and 56 will be tested for serological titers and the concentration of interferon-gamma. The incidence of diarrhea and respiratory diseases and the duration of each event will be also recorded. For this purpose, a system of visual evaluation of feces, based on a fecal score and a respiratory assessment score will be used (McGuirk, 2008). Canola expeller meal, linseed expeller meal, and starters will be nutritionally analyzed by NIRS, requesting the CNCPS platform. Fatty acid profiles in serum and feed will be analyzed by HPLC. Bovine serum resolvin-E1, protectin (CD59), haptoglobin, TNF-α, and interleukin-1 and 6 and interferon gamma will be assayed by commercial ELISA kits (MyBioSource, Inc., San Diego, CA, USA), according to standard protocols recommended by the company. From sample of d 7, serum total protein, as an indicator of colostrum management, will be assessed by a clinical refractometer (g/dL). The concentration of total proteins will be used as a co-variable for the different statistical models.Statistical analysisAverage daily gain and feed efficiency from 0-28 d, 28-56 d, and 0-56 d will be statistically analyzed by a GLM ANOVA. Body weight over time, feed intakes, and blood metabolites will be analyzed by ANOVA for repeated measures, constructing a mixed model, considering the calf as random effect nested within the treatment group. Independent variables will be the effect of treatment, parity number of the dam, and serum total protein concentration of calves at first week of life. For all models, the best goodness of fit will be specified according to the Schwarz's Bayesian Criterion (Littell et al., 1998). Least squares means ± SEM will be reported. Significant effects will be considered when P ≤ 0.05. A tendency will be considered when the P value is between 0.05 and 0.1. Because the variable time is quantitative, treatment will be also modeled as a polynomial function of time. This gives smoothed trends over time and yields equations than can be used for comparing treatments at specific times, even though the effect of interaction treatment by time is not significant when time is considered as class variable (Littell et al., 1996). Disease incidence will be analyzed through a logistic regression model considering as explanatory variables: effect of treatment (CAN, LIN), effect of dam's parity (1, 2, 3 or more), effect of calf serum total protein (g/dl). Statistical analyses will be conducted using the corresponding procedures (PROC MIXED and PROC LOGISTIC) of SAS 9.4 for windows (2012).