Corn crops require large amounts of resources that affect the
environmental sustainability of dairy cow farming systems. The aim of the
study was thus to investigate the effects of the replacement of corn silage
(CS) with triticale silage (TS) by evaluating blood and productive
parameters. The study lasted 7 weeks and involved two groups of 20
Italian Holstein Friesian dairy cows that were homogeneous in terms of
parity (3±1.5), days in milk (DIM) (150±85.0), and daily
milk production (26±4.6 kg).
Chemical analysis of feeds was carried out weekly. Dry-matter intake was
estimated daily. At the beginning and end of the trial, haematological,
metabolic, and immunological parameters were analysed. At the same, time
body weight and body condition score were measured. Milk characteristics
were also analysed weekly. Statistical analysis was performed by ANOVA on data of the second sampling, and a non-parametric test was performed to analyse BCS.
Regarding the haematological parameters in the two groups, only lymphocyte
values were not in the normal range (2.86 and 2.50×109 L
for CS and TS, respectively). Metabolic parameters were in the normal range
except for blood ureic nitrogen (BUN; 13.65 and 14.04 mgdL-1), non-esterified
fatty acids (NEFAs; 21.40 and 31.93 µmolL-1), and Cl (91.99 and 93.50 mmolL-1). Hair cortisol was low (0.94 and 0.91 pgmg-1), indicating the absence of stress signs, as confirmed by the results
of other immunological parameters (serum
lysozyme (SL), bactericidal activity (SBA), haptoglobin (HP), and oxygen free radicals (OFRs)).
Statistical differences were not found either for haematological or
biochemical parameters. The total replacement of CS with TS did not affect
milk yield and composition.
In conclusion, the replacement of CS by TS did not give rise to significant
modifications in the parameters investigated and did not alter the health
status of the animals, thus suggesting the feasibility of its introduction
into the diet of mid-lactation dairy cows.
Introduction
Given the urgent need for the rational management of resources, greenhouse
gases, and land use, some feed sources need to be replaced in the diet of
dairy cows. This replacement is also necessary since the corn crops widely
employed as silage for dairy cow feeding have a negative impact on resource
requirements and pollution (Harper et al., 2017). Moreover, the use of corn
in the feeding system of dairy cows needs to be converted due to the high
likelihood of contamination from mycotoxin (Migliorati et al., 2017).
One possible replacement crop is triticale since it has a high yield, adapts
well to a wide range of soil types and environments, and shows a low
susceptibility to the common fungal diseases of cereals (Randhawa et al.,
2015), together with a low water consumption (Cosentino et al., 2015).
Triticale is increasingly used for livestock due to its nutritional
qualities. However, triticale starch shows a higher level of rumen
digestibility than corn starch (93 % vs. 90 %) (Krieg et al., 2017), and
it is advisable to avoid sudden changes in the diet, especially when it is
added in high quantities (Myer and Lozano del Rio, 2004).
Health and productivity are closely connected. Blood metabolites are
particularly informative regarding the animal's response to nutritional
challenges (Satyendra and Om, 2016). Haematological and immunological
parameters provide information on the animal's health condition, whereas
hair cortisol highlights the activity of the hypothalamus pituitary adrenal
axis (Comin et al., 2011) in response to stressors. Lastly, body weight
(BW), body condition score (BCS), and milk quanti-qualitative characteristics
represent the productive response.
Studies on the feasibility of the partial introduction of triticale in the
diet of dairy cows in the transition period have been carried out (Mikula et al., 2011; Cosentino et al., 2015). The aim of this study was thus to assess
the health of dairy cows following the total replacement of corn silage with
triticale silage by evaluating the haematological, metabolic, immunological,
and productive parameters in cows during mid-lactation.
Material and methods
The trial was carried out on the experimental dairy farm of the University
of Pisa. Animals were handled as outlined in accordance with the guidelines
of the European Union directive 2010/63/EU for animal experiments.
Forty multiparous healthy Italian Holstein Friesian dairy cows in
mid-lactation were used in the experiment. No animal enrolled had
experienced a change in social group or had been affected by any diseases in
the period before the study.
The cows were managed in a free-stall system, milked twice daily, and fed a
total mixed ration corresponding to the diet containing corn silage (CS),
described in Table 1.
Ingredients and chemical composition of the experimental diets
(mean ± standard deviation).
Diets CS TS Ingredients (% DM)meanSDmeanSDAlfalfa hay, first cut8.780.458.370.48Alfalfa hay, second cut18.051.1617.211.32Concentrate∗21.461.5720.461.57Cereal mix25.851.9624.651.76Corn silage25.851.960Triticale silage029.301.41Chemical composition (% of DM)Dry matter48.92.046.61.7Crude protein13.11.113.21.3Ether extract3.30.43.31.4Ash5.60.75.30.4Neutral detergent fibre (NDF)36.82.935.32.4Acid detergent fibre (ADF)22.52.520.72.7Acid detergent lignin (ADL)14.31.414.61.7Non-protein nitrogen (NPN)1.40.11.50.1Soluble carbohydrates4.20.14.40.1Starch25.81.832.52.0Metabolizable protein gkg-1100.15.6100.14.7Titratable acidity (meqg-1)7.20.26.40.1Lactic acid (%DM)4.80.45.10.1Acetic acid (%DM)2.50.24.90.3Propionic acid (%DM)0.20.00.40.0Butyric acid (%DM)0.00.00.00.0Metabolizable energy MJkg-19.80.59.60.4Net energy of lactation MJkg-15.90.25.90.2
At the beginning of the trial (T0), two groups of 20 cows were allocated
randomly. The study lasted 7 weeks and involved two groups of 20 cows
that were homogeneous in terms of parity (3±1.5), days in milk (DIM)
(150±85.0), daily milk production (26±4.6 kg), and BCS (3.01±0.26 and 3.04±0.37 for CS and triticale silage (TS), respectively). The control
group consumed the usual diet containing CS. The other group
received a diet in which the corn silage had been totally replaced with TS. The trial ended after 7 weeks (T1). Water was
offered ad libitum.
After harvest time (middle of May), triticale plants (Orval variety) were ensiled in silos, filled in 1 working day and sealed with polyethylene
film. The inoculant, Pioneer 11A44® containing LN
4637 Lactobacillus buchneri 100 %, was applied on forage. After 3 months
of storage, silos were unloaded.
The ingredients and chemical composition of the experimental diets are
reported in Table 1. At T0, the CS and TS groups were homogeneous in terms
of parity (3±1.5), days in milk (DIM) (150±85.0), and daily
milk production (26±4.6 kg).
Dry-matter intake (DMI) was estimated daily, by weighing the residue of the
ration. The animals were fed in groups. Feed efficiency was calculated per
dietary group by the ratio between kilograms of daily milk and kilograms of
feed dry matter (DM) consumed. DMI and feed efficiency did not differ between the two
groups.
Feed samples were collected every week for chemical analysis. The following
analyses were performed: neutral detergent fibre (NDF), acid detergent fibre (ADF), and acid detergent lignin (ADL) (Van Soest et al., 1991), crude protein,
ash, ether extract (AOAC, 2000), non-protein nitrogen (NPN), soluble
nitrogen, nitrogen in NDF residues (NDFIP) and nitrogen in ADF residue (ADFIP)
(Licitra et al., 1996), starch (McCleary et al., 1997), and soluble
carbohydrates (Dubois et al., 1956).
Individual milk production was measured daily, and analyses of fat, protein,
lactose, urea, and somatic cell count were performed weekly. Milk samples
were analysed for fat, protein, and lactose by infrared analysis (Milkoscan
133 B; Italian Foss Electric, Padua, Italy). The somatic cell count (SCC)
was calculated with a Fossomatic 215 cell counter (Foss Electric, 3400
Hillerod, Denmark). Data were transformed into linear scores according to
Wiggans and Shook (1987).
Milk was sampled in the morning and was stored at 4 ∘C with a
preservative (Bronopol solution, Lanxess, Corporation, Pittsburgh, PA) until
the analysis.
At T0 and at T1, in the morning, immediately after feeding, blood samples
were collected in quiet conditions from 10 cows randomly selected in each
group by the farm veterinarian. Blood samples were taken from the jugular
vein minimizing stress. Antiseptic gauze was applied to remove superficial
dirt and debris. The jugular vein was visualized by applying pressure at the
base of the jugular groove. The needle was firmly inserted into the skin and into the vein at a 20∘ angle. Vacutainer tubes either with or without K3-ethylenediamine tetra-acetic acid (EDTA) as anticoagulant
were employed.
The samples were kept in ice boxes and immediately sent to the laboratory.
The complete blood count was measured by the laboratory of the Veterinary
Science Department of Pisa using a CELL-DYN 3500® automated
haematology analyser (Abbott, Minneapolis, USA). The following were
analysed: red blood cells (RBCs), haematocrit (HCT), haemoglobin (HGB), mean
corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), reticulocytes
(RETIC), white blood cell count (WBC), neutrophils (NEUs), lymphocytes (LYMs), monocytes (MONs), eosinophils (EOSs), basophils (BASs), and blood platelets
(PLTs).
The following metabolic and immunological parameters were analysed by the Istituto Zooprofilattico Sperimentale Lazio e Toscana (IZSLT):
alanine aminotransferase (ALT), aspartate aminotransferase (AST),
beta-hydroxybutyric acid (BHBA), blood ureic nitrogen (BUN), non-esterified
fatty acids (NEFAs), total proteins (TPs), creatinine (Creat), calcium (Ca),
chlorine (Cl), phosphorus (P), potassium (K) and sodium (Na), and serum
lysozyme (SL). Bactericidal activity (SBA) was determined according to
validated procedures using a bacteriological assay (Osserman and Lawlor,
1966; Bonizzi et al., 1989; Ponti et al., 1989; Amadori et al., 2002).
Haptoglobin (HP) and oxygen free radicals (OFRs) were monitored by a
colorimetric method (Giuliotti et al., 2017).
At T0 and T1, hair samples were carefully cut from the tail switch using
clippers and frozen at a temperature of -20∘C to prevent the
presence of lice and were analysed according to Giuliotti et al. (2017).
Blood and hair samples were collected during daily routine activities in
order not to disturb the animals.
At the same time, BW and BCS were
recorded. BCS was recorded by the same observer using the 1–5 scale
according to Ferguson et al. (1994), along with an increasing level of
fattening.
Data were analysed with the following linear model, using JMP software
(S.A.S., 2002):
yij=μ+Di+b(xij-x)+eij,
where yij is haematological, biochemical, and immunological parameters,
milk yield and composition, and body weight; Di is the fixed effect of the ith diet (CS and TS); Tj=β is the linear regression
coefficient between yij and xij, xij is the covariate value corresponding to yij, x is the mean of xij, and eij is the residual error.
BCS was analysed by the Wilcoxon non-parametric test.
Results and discussion
BW (Table 2) and BCS did not differ significantly. BCS mean values were 3.01±0.29 and 3.04±0.31 for the CS and TS groups, respectively.
McQueen and Fillmore (1991) reported similar BW results, while Mikula et al.
(2011) reported similar BCS values.
Haematological parameters of each sampling in the two experimental
groups.
Normal rangeUMCSTSSEMP valueBWkg688.07684.0612.120.85RBC4.47–9.35×1012 L5.996.230.110.15HCT22.5–39.9%28.1528.720.840.64HGB7.4–12.8gdL-19.5810.080.190.08MCV40.4–56.4fL48.5748.991.130.79MCH11.5–18.5pg16.1216.220.210.72RETIC0–3.0KµL-11.441.420.300.96WBC2.71–17.76KµL-17.667.500.520.83NEU1.1–5×109 L3.783.790.500.99LYM3.2–6.8×109 L2.86↓2.50↓0.260.36MON0.1–0.8×109 L0.410.480.080.57EOS0.1–2.2×109 L0.500.550.140.82BAS0–0.2×109 L0.180.090.120.58PLT147–663KµL-1348.30363.5043.410.81
Normal ranges were provided by the laboratory of the Department of Veterinary Science of Pisa.
↑ Values over the threshold of the normal range. ↓
Values under the threshold of the normal range.
RBCs – red blood cells; HCT – haematocrit; HGB – haemoglobin; MCV – mean
corpuscular volume; MCH – mean corpuscular haemoglobin; WBC – white blood
cell count; NEUs – neutrophils; LYM – lymphocyte; MONs – monocytes; EOSs – eosinophils; BASs – basophils; PLTs – blood platelets; SEM – standard error of mean.
UM (unit of measurements): kg (kilogram), %
(percentage), gdL-1 (grams per decilitre),
fL (femtolitre), pg (picogram), KµL-1 (thousand per microlitre),
L (litre).
No significant differences were detected for the haematological parameters
(Table 2). Almost all the values fell within the range of reference for
healthy dairy cows, with only LYM not in this range. A moderate lymphopenia
is a common finding in stressed animals (Gleeson et al., 2007); however, in the
present survey this condition was not confirmed by the outcome of the other
parameters such as hair cortisol level and other immunological parameters.
Lymphopenia has been described during acute viral or bacterial infections
(Jones and Allison, 2007); however, the cows in our study did not present
these conditions. In any case, lymphopenia is not attributable
to the diet.
Regarding the metabolic parameters (Table 3), no significant differences
were found. This was also confirmed in a study by Gorelik et al. (2020), in
which the introduction of triticale in the diet of cattle did not affect any
of the examined metabolic parameters (AST, TP, Ca, P).
Biochemical and immunological parameters of each sampling in the
two experimental groups.
Normal ranges were provided by the laboratory of IZSLT. SEM stands for standard error of the mean. ∗ No laboratory reference range is available.
∗∗ U. Carr. is an arbitrary unit; 1 U. Carr. is equivalent
to 0.08 mg of H2O2 per mg dl-1.
↑ Values over the threshold of the normal range. ↓
Values under the threshold of the normal range.
ALT – alanine aminotransferase; AST – aspartate aminotransferase; BHBA
(beta-hydroxybutyric acid; BUN – nitrogen ureic; NEFAs – non-esterified fatty
acids; TPs – total proteins; Creat – creatinine;
Ca – calcium; Cl – chlorine; P – phosphorus; K – potassium; Na – sodium; SL – serum lysozyme; SBA – bactericidal activity; HP – haptoglobin; OFRs – oxygen free radicals; and
hair cortisol.
UM (unit of measurements): UL-1 (unit per litre),
mgdL-1 (milligram per decilitre),
µmolL-1 (micromole per litre), gdL-1 (gram
per decilitre), mmolL-1
(millimole per litre), µgmL-1 (microgram per millilitre); U.carr (Carratelli
unit); % (percentage); pgmg-1 (picogram per milligram).
Only BUN, NEFA, and Cl values were not in the normal range in the two
groups.
NEFA together with BHBA is considered important in evaluating the negative
energy balance in dairy cows. In our case, this was not a problem because
the NEFA values were low and BHBA was in the normal range.
High plasma NEFA levels with other parameters such as BHBA and OFR (Herdt,
2000) could be indices of inflammation. In our study, no critical situation
regarding these parameters was shown (Table 3) (Giuliotti et al., 2017;
Benvenuti et al., 2018). In fact, although NEFA was far below the normal
threshold, Cozzi et al. (2011) reported that in mid-lactation NEFA
concentration decreases when the energy balance turns positive; in any
case, Oetzel (2004) reported that low NEFA concentrations are not
biologically important.
BUN values were also found to be under the threshold. BUN is strictly
related to protein because the urea derived from nitrogen deamination of
amino acids is not utilized for milk synthesis (Kohn, 2007). Low BUN levels
can sometimes be explained by a deficient protein and energy intake (Lee et
al., 1978); however, in our trial the diets were adequately formulated
(Table 1) for low-producing dairy cows. This occurrence has been noticed by
Nozad et al. (2012), who, in a study on low- and high-producing cow (average
daily milk production 29 and 32 kgd-1), found the lowest values of BUN in
the cow with the lowest milk yield.
Most minerals are regulated in the body through homeostatic processes and
their concentrations are rarely due to an insufficient supply in the diet
(Van Saun, 2008). In our study, Cl values were slightly under the normal
range in the two groups. Skrzypczak et al. (2014) reported a chlorine concentration in the blood ranging from 93 to 107 mmolL-1 in healthy cows. The
same authors reported that the concentration of Cl is associated with the Na
concentration, which however was in the normal range. The other minerals (Ca
and K) fell within the normal range, thus not indicating a health
impairment.
SL, SBA, and HP represent a nonspecific cellular immune response. Our results
regarding the first two parameters indicated a slightly altered immune
response in the experimental group. It is well known that the functionality
of the immune system can be influenced by diet (Dänicke et al., 2018).
An alteration in these parameters may indicate inappropriate feed
management in addition to inadequate hygienic and sanitary conditions of the
herd (Bonizzi et al., 2003). As SL is involved in the immune system, it is
one of the most predictive parameters of disease. Variations in SL levels
have been found in response to inflammation or metabolic stress-related
conditions in early lactation (Trevisi et al., 2012). Bonizzi et al. (2003)
also reported a decrease in SL in cows during the transition period.
Regarding SBA, some authors have reported that values around 90 %
represent a sign of altered physiological conditions, thus indicating a
predisposition to developing diseases conditioned by stressful events
(Amadori et al., 2002). Despite all these considerations, as statistical
differences were not found between the two groups, the low SL and SBA values
were not ascribable to the triticale silage.
Investigating hair cortisol is important due to its relationship with
chronic stress (Accorsi et al., 2008). The values that we found for hair
cortisol were lower than those found in the literature. Del Rosario et al.
(2011) reported hair cortisol concentrations equal to 12.15±1.85pgmg-1 in 2-year-old cows, and Burnett et al. (2014) found a cortisol level
equal to 11.0±1.2pgmg-1 in lactating dairy cows. Benvenuti et al.
(2018) observed higher values in dairy cows reared in an open-stall system.
The total replacement of CS with TS did not affect milk yield and
composition (Table 4). Our results on milk yield confirmed the study by
Cosentino et al. (2015) and Migliorati et al. (2017), who found no
differences when replacing corn with triticale and barley silage, respectively. On the other hand, Harper et al. (2017) reported a milk yield
decrease as a consequence of a partial substitution of corn silage with
triticale silage. This contrasting result could be due to the sensitivity of
dairy cows to modifications in the diet in high-yielding dairy cows
(Enemark, 2008).
The introduction of triticale in the diet did not affect the milk
composition, in agreement with other authors (McQueen and Fillmore, 1991; Mikula et al., 2011; Harper, 2017).
Conclusions
Our results showed that in our experimental conditions, the complete
substitution of corn silage with triticale silage did not induce differences
in the investigated blood parameters and thus did not impair the health of
the animals. In fact, hair cortisol, which is an indicator of chronic
stress, was not influenced by the change in diet and showed a low
concentration. In conclusion, since most of the alterations observed were
not related to the diet and the productive parameters were unchanged,
triticale silage would seem to be a valid replacement for corn when used in
non-high-producing dairy cows.
Data availability
The datasets generated and/or analysed during the current study are
available from the corresponding author on reasonable request.
Ethical statement
This study was performed according to the Italian and European regulations
on animal welfare (Directive 2010/63/EU of the European Parliament and of
the Council of 22 September 2010 on the protection of animals used for
scientific purposes).
Author contributions
Each author participated in the study. LG, MNB, and AM conceived and designed the experiment. LG, MNB, AM, PAA, and AC performed the experiments. MNB and
GC analysed the data. LG, MNB, and GC wrote the paper.
Competing interests
The contact author has declared that neither they nor their co-authors have any competing interests.
Disclaimer
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Financial support
This work was supported by the Tuscany Region Rural Development Fund.
Review statement
This paper was edited by Manfred Mielenz and reviewed by Elisabetta Salimei and one anonymous referee.
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