Trop Anim Health Prod (2015) 47:1307–1312 DOI 10.1007/s11250-015-0864-x
REGULAR ARTICLES
Performance and carcass yield of crossbred dairy steers fed diets with different levels of concentrate Gabriel Santana da Silva 1 & Antônia Sherlanea Chaves Véras 1 & Marcelo de Andrade Ferreira 1 & Wilson Moreira Dutra Jr. 1 & Maria Luciana Menezes Wanderley Neves 1 & Evaristo Jorge Oliveira Souza 2 & Francisco Fernando Ramos de Carvalho 1 & Dorgival Morais de Lima Jr. 3
Received: 24 October 2014 / Accepted: 31 May 2015 / Published online: 12 June 2015 # Springer Science+Business Media Dordrecht 2015
Abstract The objective of this study was to evaluate the influence of diets with increasing concentrate levels (170, 340, 510 and 680 g/kg of total dry matter) on dry matter intake, digestibility, performance and carcass characteristics of 25 Holstein-Zebu crossbred dairy steers in a feedlot. A completely randomized design was used, and data were submitted to analysis of variance and regression. The dry matter intake and digestibility coefficients of all nutrients increased linearly. The total weight gain and average daily gain added 1.16 kg and 9.90 g, respectively, for each 10 g/kg increase in concentrate. The empty body weight, hot carcass weight and cold carcass weight responded linearly to increasing concentrate. The hot carcass yield and cold carcass yield, gains in empty body weight and carcass gain were also influenced, as were the efficiencies of carcass deposition and carcass deposition rate. It is concluded that increasing concentrate levels in feedlot diets increase the intake and digestibility of dry matter and other nutrients, improving the feed efficiency, performance and physical characteristics of the carcass. Furthermore and of importance concerning the climate change debate, evidence from the literature indicates that enteric methane production would be reduced with increasing concentrate levels such as those used.
* Dorgival Morais de Lima, Jr. [email protected] 1
Department of Animal Science, Universidade Federal Rural de Pernambuco, Recife, PE 52171-900, Brazil
2
Unidade Acadêmica de Serra Talhada, Universidade Federal Rural de Pernambuco, Serra Talhada, PE 56900-000, Brazil
3
Campus Arapiraca, Universidade Federal de Alagoas, Av. Manoel Severino Barbosa, s/n, Bom Sucesso, Arapiraca, AL, Brazil 57309-005
Keywords Digestibility . Feed efficiency . Dairy bulls . Energy levels
Introduction Brazil is the second largest producer of beef in the world; Brazilian beef production increased from 5.5 million tons in 1991 to 9.0 million tons in 2011 (USDA 2011). In order to meet the demands of the domestic and export markets for bovine meat, the utilization of feedlots enhances and streamlines the production process since it reduces the time required for an animal to reach its slaughter age (Missio et al. 2009a). Therefore, it is a fast and efficient way found by producers to finish beef cattle. High-concentrate diets have been utilized in feedlots in order to improve feed efficiency, among other reasons (Gionbelli et al. 2012). Furthermore, an increase in the level of concentrate in the diet can also reduce the production of methane by the ruminant (Knapp et al. 2014). Regarding the supply of finishing cattle in Brazil, there is a growing deficit of beef calves, making the use of animals from dairy herds an option (Alves et al. 2004; Ferraz and Felício 2010). In the semiarid region of Brazil, dairy farming is considered one of the main economic alternatives. Exploitation of animals from this activity, which in general is the result of crosses of continental European breeds with Zebu cattle, becomes an opportunity for producers, given the difficulty in generating viable regional livestock, which is constantly associated with prolonged off-season periods generated by climatic seasonality. It is notable that in the Brazilian northeast, the effective dairy cattle herd is larger than that of beef cattle (ANUALPEC 2013).
1308
Trop Anim Health Prod (2015) 47:1307–1312
Table 1 Composition of the concentrate and nutritional components of the concentrate and hay Concentrate ingredients
g/kg
Maize grain Soybean meal
671 150
Wheat bran
123
Urea Sulphate of ammonia
13 1
Sodium chloride Mineral mixa Limestone Soda
10 10
Magnesium oxide
5
Materials and methods Site, period and facilities
7 10
Nutritional components Dry matterb Organic matterc Crude proteinc Ether extractc Total digestible nutrientsc,d Total carbohydratesc Non-fibrous carbohydratesc Neutral detergent fibrec Acid detergent fibrec
Concentrate 896 920 190 340 780 730 550 170 560
Hay 890 930 930 230 560 860 790 710 280
a
Mineral mix composition: Ca 132.72 (g/kg); P 96.86; (g/kg); S 38.00 (g/kg); Co 66.42 (mg/kg); Cu 1.810.44 (mg/kg); Fe 2.846.46 (mg/kg); I 89.55 (mg/kg); Mn 1774.63 (mg/kg); Se 14.92 (mg/kg); Zn 4.298.51 (mg/kg); F 968.60 (mg/kg)
b
Grammes per kilogramme (g/kg) natural matter
c
Grammes per kilogramme (g/kg) dry matter
d
Estimate form Weiss (1999)
Research is needed to evaluate the possibility of using dairy males in local meat production, in particular Holstein-Zebu, finished under tropical conditions (Hessle et al. 2007). Table 2 Nutritional composition of the experimental diets
Our objectives were to evaluate the intake, apparent digestibility, performance and carcass characteristics of crossbred steers in a feedlot consuming high-concentrate diets.
The experiment was conducted at the Academic Unit of Serra Talhada (UAST) belonging to the Federal Rural University of Pernambuco (UFRPE), the state of Pernambuco, Brazil, between May and November of 2011. The study had a total duration of 112 days, divided into four 28-day periods. The region has irregular rainfall, with a 700-mm annual average, of which 0.55 occurs between March and June. In addition, the thermal regime is characterized by high temperatures with maximum values of 29.6 °C (INMET 2005). Animals were kept in individual stalls (3×9 m) surrounded by smooth wire and with floors of fibre-cement tiles. Each stall had a feeder (1.0 m long). Each pair of stalls shared an automatic water dispenser. Animals and experimental diets The study utilized 25 crossbred Holstein-Zebu bulls, with an initial body weight of 343.5 ± 38.7 kg and mean age of 27 months, purchased from a commercial herd. Initially, the animals were weighed, identified and treated against endo- and ectoparasites. After a period of adaptation (40 days) receiving the same diet, the animals were randomly distributed in treatments containing 170, 340, 510 and 680 g/kg of concentrate, based on the total dry matter of the diet (Tables 1 and 2), as a total mixed ration.
Ingredients
Concentrate levels (g/kg DM) 170
340
510
680
Organic matter (g/kg DM) Crude protein (g/kg DM) Ether extract (g/kg DM) Total digestible nutrientsb (g/kg DM) Total carbohydrates (g/kg DM) Non-fibrous carbohydrates (g/kg DM)
890 930 120 480 570 810 140
890 920 130 560 630 760 260
890 920 140 640 680 700 380
890 920 160 710 730 650 510
Neutral detergent fibre (g/kg DM) Acid detergent fibre (g/kg DM)
620 240
520 210
430 170
340 130
Nutritional components (g/kg DM) Dry mattera
a
Grammes per kilogramme (g/kg) natural matter
b
Determined form Weiss (1999)
Trop Anim Health Prod (2015) 47:1307–1312 Table 3
1309
Nutrient intake of crossbred cattle depending on the increasing levels of concentrate Concentrate levels (g/kg DM)
Dry matter (kg/day) a
Dry matter (g/kg BW ) Dry matter (g/kg BW0. 75a) Organic matter (kg/day) Neutral detergent fibre (kg/day) Neutral detergent fibre (g/kg BWa) Crude protein (kg/day) Non-fibre carbohydrates (kg/day) Total digestible nutrients (kg/day)
170
340
510
680
CV (%)
r2
P
R.E.
8.4 21.0 94.5
9.5 24.0 105
10.2 24.0 110
10.5 25.0 112
16.7 7.2 8.8
0.930 0.850 0.881
0.0490 0.0044 0.0075
y=7.9164+0.0404x y=2.064+0.0066x y=91.316+0.3321x
7.9 5.1 13.0
8.9 6.0 12.0
9.5 4.4 11.0
9.7 3.7 9.0
16.7 16.3 6.2
0.921 0.935 0.960
0.0598 0.0049 0.0000
y=7.431+0.0359x y=5.7824−0.0286x y=1.4794−0.0085x;
0.9 1.3
1.2 2.3
1.5 3.2
1.6 4.0
16.9 18.6
0.994 0.991
0.0001 0.0000
y=0.704+0.0141x y=0.4265+0.0538x
5.9
6.7
7.9
8.3
17.5
0.976
0.0038
y=5.05+0.0501x
R.E. regression equations a
Body weight
Diets were formulated according to the recommendations of the NRC (2000) for weight gains of 1 kg/day. The forage provided was Tifton 85 hay (Cynodon spp.). The concentrate was mixed in ground form with the hay, which was previously ground via a 10-mm screen in a chopping machine (Trapp®— Trf 400f—2cv). Fresh water was continuously available to the animals. Feeding was performed twice a day at 0900 and 1600 hours to allow ad libitum intake and adjusted to 5 % leftover every day.
production, indigestible acid detergent fibre (iADF) was used as an internal indicator. Faecal samples, food and leftovers were ground in a Willey-type mill with a 2-mm-mesh sieve and packed in TNT bags (TNT—100 μ) with dimensions of 4×5 cm. The samples were placed in bags at 20 mg dry matter/cm2 (5 g per bag) of surface (Nocek 1988) and incubated in the rumen of fistulated cattle for 264 h, following the recommendations of Casali et al. (2008). Composite samples of ingredients, leftovers and faeces were ground in a Willey-type mill with a 1-mm-mesh sieve for laboratory analyses: dry matter (AOAC 1990, method 943.01), mineral matter (AOAC 1990, method 942.05), crude protein (AOAC 1990, method 920.87), ether extract (AOAC 1990, method 920.39A), neutral detergent fibre and acid detergent fibre, methodology described by Van Soest et al. (1991), modified by Ankom Technology, Fairport, NY (Pell and Schofield 1993). For estimation of total carbohydrates, non-fibre carbohydrates and total digestible nutrients, the equations in Sniffen et al. (1992), Hall (2000) and Weiss (1999) were used, respectively.
Sampling, collection and laboratory analysis The quantities of food provided and leftovers were recorded daily. Samples were collected weekly from the ingredients that made the concentrates, hay and leftovers per animal. Weekly samples were pre-dried in a forced ventilation oven at 55–60 °C for 72 h. At 100 days into the experiment, samples were collected from the digestibility trial for 10 days to determine the apparent digestibility of nutrient. To estimate the faecal dry matter Table 4
Coefficients of apparent digestibility of nutrients and total digestible nutrient content depending on the increasing levels of concentrate Concentrate levels (g/kg DM) r2
P
R.E.
1.4 4.7 9.4 7.6 2.1
0.976 0.956 0.953 0.991 0.957
0.000 0.001 0.000 0.000 0.000
y=58.035+0.3228x y=67.534+0.1634x y=45.298+0.5838x y=35.4999+0.5308x y=57.396+0.3123x
5.0 344.0
0.830 0.997
0.000 0.000
y=58.056+0.3456x y=52.585+0.3043x
170
340
510
680
CV (%)
Dry matter Neutral detergent fibre Crude protein Ether extract Organic matter
0.62 0.71 0.53 0.44 0.61
0.70 0.72 0.69 0.54 0.70
0.74 0.76 0.73 0.63 0.73
0.79 0.79 0.85 0.71 0.78
Non-fibre carbohydrates Total digestible nutrientsa
0.61 0.57
0.74 0.63
0.76 0.68
0.79 0.73
R.E. regression equations a
Observed form Weiss (1999)
1310 Table 5
Trop Anim Health Prod (2015) 47:1307–1312 Performance of crossbred cattle in feedlot due to rising levels of concentrate Concentrate levels (g/kg DM) 170
340
510
680
CV (%)
r2
P
R.E.
344
344
343
343
12.3
–
–
N.S.
Final body weight (kg)
449
459
489
504
12.5
–
–
N.S.
Total weight gain (kg) Average daily gain (kg/day)
105 0.86
115 0.95
145 1.22
161 1.34
18.6 19.8
0.965 0.964
0.001 0.001
y=82.5+1.1588x; y=0.6723+0.0099x
10.3
10.0
12.0
12.7
9.4
0.822
0.002
y=8.9688+0.054x
Initial body weight (kg)
Feed efficiency
N.S. means not significant. Indicate significant differences according to Tukey’s test (P≤0.05) R.E. regression equations
Performance evaluation, slaughter procedures and carcass evaluations After the adaptation period, five animals were slaughtered to obtain initial carcass weights in order to allow estimates of their respective gains. At the end of each 28-day period, the remaining animals were weighed after solid fasting for approximately 16 h to determine total weight gain and average daily gain. Feed efficiency was calculated as the ratio between the average daily gain (kg/day) and dry matter intake in kilogrammes per day. After 112 days, all animals were slaughtered. Slaughter was conducted in the city slaughterhouse of Serra Talhada, Pernambuco, Brazil, and followed the normal procedures of a slaughterhouse under state inspection. The carcass of each animal was divided into two half-carcasses, which were weighed to obtain the hot carcass yield and then cooled in a cold chamber at ±4 °C for 24 h. After this period, the half-carcasses were removed from the cold chamber and weighed to determine the cold carcass weight and cold carcass yield. The carcass gain was calculated considering the carcass weight obtained at slaughter minus the initial parameters of the reference animals. Table 6
The efficiency of carcass deposition was calculated as the ratio between the carcass gain and dry matter intake. The carcass deposition rate in kilogrammes per day was obtained by the ratio between the carcass gain and the days in the feedlot. Experimental design and statistical analysis The experimental design was completely randomized. Data were submitted to analysis of variance and regression using SAS statistical software version 9.1 (SAS Inst. Inc. 2009). The criterion used to select the model was the coefficient of determination (r2, in g/kg), and significance was estimated through the F test.
Results Dry matter intake (kg/day) increased linearly with the addition of concentrate (Table 3). Likewise, intake as a percentage of body weight (g/kg BW) and intake in terms of metabolic body weight (g/kg BW0.75).
Features of deposition and carcass yield of crossbred cattle depending on the increasing levels of concentrate Concentrate levels (g/kg DM) 170
340
510
680
CV (%)
r2
P
R.E.
Hot carcass weight (kg) Cold carcass weight (kg) Hot carcass yield (g/kg) Cold carcass yield (g/kg) Carcass gain (kg) Efficiency of carcass depositiona
245 237 0.54 0.52 85.6 8.3
255 251 0.55 0.54 99.9 8.5
282 277 0.57 0.56 125.9 10.2
290 285 0.57 0.56 134.0 10.6
13.7 13.4 3.0 2.0 31.6 20.3
0.954 0.965 0.858 0.858 0.965 0.904
0.041 0.027 0.004 0.000 0.027 0.043
y=272.04+0.9633x y=219.54+1.0074x y=53.42+0.0671x y=51.693+0.0798x y=68.54+1.0074x y=7.2933+0.0496x
Carcass deposition rate (kg/day) Gastrointestinal content (kg)
0.7 47.4
0.8 41.8
1.1 39.5
1.1 31.7
34.3 20.3
0.957 0.960
0.036 0.008
y=0.5644+0.0086x y=52.396−0.2894
R.E. regression equations a
The efficiency of carcass deposition was calculated as the ratio between the carcass gain and dry matter intake
Trop Anim Health Prod (2015) 47:1307–1312
The crude protein and total digestible nutrient intakes showed the same trend as DMI, rising 14.1 and 50 g, respectively, for every 10 g/kg concentrate. The neutral detergent fibre intake was linear and negatively influenced by the inclusion of concentrate in the diet, falling by 29 g with every increase of 10 g/kg concentrate. The results for apparent digestibility of nutrients are shown in Table 4. A positive linear and significant behaviour (P
REGULAR ARTICLES
Performance and carcass yield of crossbred dairy steers fed diets with different levels of concentrate Gabriel Santana da Silva 1 & Antônia Sherlanea Chaves Véras 1 & Marcelo de Andrade Ferreira 1 & Wilson Moreira Dutra Jr. 1 & Maria Luciana Menezes Wanderley Neves 1 & Evaristo Jorge Oliveira Souza 2 & Francisco Fernando Ramos de Carvalho 1 & Dorgival Morais de Lima Jr. 3
Received: 24 October 2014 / Accepted: 31 May 2015 / Published online: 12 June 2015 # Springer Science+Business Media Dordrecht 2015
Abstract The objective of this study was to evaluate the influence of diets with increasing concentrate levels (170, 340, 510 and 680 g/kg of total dry matter) on dry matter intake, digestibility, performance and carcass characteristics of 25 Holstein-Zebu crossbred dairy steers in a feedlot. A completely randomized design was used, and data were submitted to analysis of variance and regression. The dry matter intake and digestibility coefficients of all nutrients increased linearly. The total weight gain and average daily gain added 1.16 kg and 9.90 g, respectively, for each 10 g/kg increase in concentrate. The empty body weight, hot carcass weight and cold carcass weight responded linearly to increasing concentrate. The hot carcass yield and cold carcass yield, gains in empty body weight and carcass gain were also influenced, as were the efficiencies of carcass deposition and carcass deposition rate. It is concluded that increasing concentrate levels in feedlot diets increase the intake and digestibility of dry matter and other nutrients, improving the feed efficiency, performance and physical characteristics of the carcass. Furthermore and of importance concerning the climate change debate, evidence from the literature indicates that enteric methane production would be reduced with increasing concentrate levels such as those used.
* Dorgival Morais de Lima, Jr. [email protected] 1
Department of Animal Science, Universidade Federal Rural de Pernambuco, Recife, PE 52171-900, Brazil
2
Unidade Acadêmica de Serra Talhada, Universidade Federal Rural de Pernambuco, Serra Talhada, PE 56900-000, Brazil
3
Campus Arapiraca, Universidade Federal de Alagoas, Av. Manoel Severino Barbosa, s/n, Bom Sucesso, Arapiraca, AL, Brazil 57309-005
Keywords Digestibility . Feed efficiency . Dairy bulls . Energy levels
Introduction Brazil is the second largest producer of beef in the world; Brazilian beef production increased from 5.5 million tons in 1991 to 9.0 million tons in 2011 (USDA 2011). In order to meet the demands of the domestic and export markets for bovine meat, the utilization of feedlots enhances and streamlines the production process since it reduces the time required for an animal to reach its slaughter age (Missio et al. 2009a). Therefore, it is a fast and efficient way found by producers to finish beef cattle. High-concentrate diets have been utilized in feedlots in order to improve feed efficiency, among other reasons (Gionbelli et al. 2012). Furthermore, an increase in the level of concentrate in the diet can also reduce the production of methane by the ruminant (Knapp et al. 2014). Regarding the supply of finishing cattle in Brazil, there is a growing deficit of beef calves, making the use of animals from dairy herds an option (Alves et al. 2004; Ferraz and Felício 2010). In the semiarid region of Brazil, dairy farming is considered one of the main economic alternatives. Exploitation of animals from this activity, which in general is the result of crosses of continental European breeds with Zebu cattle, becomes an opportunity for producers, given the difficulty in generating viable regional livestock, which is constantly associated with prolonged off-season periods generated by climatic seasonality. It is notable that in the Brazilian northeast, the effective dairy cattle herd is larger than that of beef cattle (ANUALPEC 2013).
1308
Trop Anim Health Prod (2015) 47:1307–1312
Table 1 Composition of the concentrate and nutritional components of the concentrate and hay Concentrate ingredients
g/kg
Maize grain Soybean meal
671 150
Wheat bran
123
Urea Sulphate of ammonia
13 1
Sodium chloride Mineral mixa Limestone Soda
10 10
Magnesium oxide
5
Materials and methods Site, period and facilities
7 10
Nutritional components Dry matterb Organic matterc Crude proteinc Ether extractc Total digestible nutrientsc,d Total carbohydratesc Non-fibrous carbohydratesc Neutral detergent fibrec Acid detergent fibrec
Concentrate 896 920 190 340 780 730 550 170 560
Hay 890 930 930 230 560 860 790 710 280
a
Mineral mix composition: Ca 132.72 (g/kg); P 96.86; (g/kg); S 38.00 (g/kg); Co 66.42 (mg/kg); Cu 1.810.44 (mg/kg); Fe 2.846.46 (mg/kg); I 89.55 (mg/kg); Mn 1774.63 (mg/kg); Se 14.92 (mg/kg); Zn 4.298.51 (mg/kg); F 968.60 (mg/kg)
b
Grammes per kilogramme (g/kg) natural matter
c
Grammes per kilogramme (g/kg) dry matter
d
Estimate form Weiss (1999)
Research is needed to evaluate the possibility of using dairy males in local meat production, in particular Holstein-Zebu, finished under tropical conditions (Hessle et al. 2007). Table 2 Nutritional composition of the experimental diets
Our objectives were to evaluate the intake, apparent digestibility, performance and carcass characteristics of crossbred steers in a feedlot consuming high-concentrate diets.
The experiment was conducted at the Academic Unit of Serra Talhada (UAST) belonging to the Federal Rural University of Pernambuco (UFRPE), the state of Pernambuco, Brazil, between May and November of 2011. The study had a total duration of 112 days, divided into four 28-day periods. The region has irregular rainfall, with a 700-mm annual average, of which 0.55 occurs between March and June. In addition, the thermal regime is characterized by high temperatures with maximum values of 29.6 °C (INMET 2005). Animals were kept in individual stalls (3×9 m) surrounded by smooth wire and with floors of fibre-cement tiles. Each stall had a feeder (1.0 m long). Each pair of stalls shared an automatic water dispenser. Animals and experimental diets The study utilized 25 crossbred Holstein-Zebu bulls, with an initial body weight of 343.5 ± 38.7 kg and mean age of 27 months, purchased from a commercial herd. Initially, the animals were weighed, identified and treated against endo- and ectoparasites. After a period of adaptation (40 days) receiving the same diet, the animals were randomly distributed in treatments containing 170, 340, 510 and 680 g/kg of concentrate, based on the total dry matter of the diet (Tables 1 and 2), as a total mixed ration.
Ingredients
Concentrate levels (g/kg DM) 170
340
510
680
Organic matter (g/kg DM) Crude protein (g/kg DM) Ether extract (g/kg DM) Total digestible nutrientsb (g/kg DM) Total carbohydrates (g/kg DM) Non-fibrous carbohydrates (g/kg DM)
890 930 120 480 570 810 140
890 920 130 560 630 760 260
890 920 140 640 680 700 380
890 920 160 710 730 650 510
Neutral detergent fibre (g/kg DM) Acid detergent fibre (g/kg DM)
620 240
520 210
430 170
340 130
Nutritional components (g/kg DM) Dry mattera
a
Grammes per kilogramme (g/kg) natural matter
b
Determined form Weiss (1999)
Trop Anim Health Prod (2015) 47:1307–1312 Table 3
1309
Nutrient intake of crossbred cattle depending on the increasing levels of concentrate Concentrate levels (g/kg DM)
Dry matter (kg/day) a
Dry matter (g/kg BW ) Dry matter (g/kg BW0. 75a) Organic matter (kg/day) Neutral detergent fibre (kg/day) Neutral detergent fibre (g/kg BWa) Crude protein (kg/day) Non-fibre carbohydrates (kg/day) Total digestible nutrients (kg/day)
170
340
510
680
CV (%)
r2
P
R.E.
8.4 21.0 94.5
9.5 24.0 105
10.2 24.0 110
10.5 25.0 112
16.7 7.2 8.8
0.930 0.850 0.881
0.0490 0.0044 0.0075
y=7.9164+0.0404x y=2.064+0.0066x y=91.316+0.3321x
7.9 5.1 13.0
8.9 6.0 12.0
9.5 4.4 11.0
9.7 3.7 9.0
16.7 16.3 6.2
0.921 0.935 0.960
0.0598 0.0049 0.0000
y=7.431+0.0359x y=5.7824−0.0286x y=1.4794−0.0085x;
0.9 1.3
1.2 2.3
1.5 3.2
1.6 4.0
16.9 18.6
0.994 0.991
0.0001 0.0000
y=0.704+0.0141x y=0.4265+0.0538x
5.9
6.7
7.9
8.3
17.5
0.976
0.0038
y=5.05+0.0501x
R.E. regression equations a
Body weight
Diets were formulated according to the recommendations of the NRC (2000) for weight gains of 1 kg/day. The forage provided was Tifton 85 hay (Cynodon spp.). The concentrate was mixed in ground form with the hay, which was previously ground via a 10-mm screen in a chopping machine (Trapp®— Trf 400f—2cv). Fresh water was continuously available to the animals. Feeding was performed twice a day at 0900 and 1600 hours to allow ad libitum intake and adjusted to 5 % leftover every day.
production, indigestible acid detergent fibre (iADF) was used as an internal indicator. Faecal samples, food and leftovers were ground in a Willey-type mill with a 2-mm-mesh sieve and packed in TNT bags (TNT—100 μ) with dimensions of 4×5 cm. The samples were placed in bags at 20 mg dry matter/cm2 (5 g per bag) of surface (Nocek 1988) and incubated in the rumen of fistulated cattle for 264 h, following the recommendations of Casali et al. (2008). Composite samples of ingredients, leftovers and faeces were ground in a Willey-type mill with a 1-mm-mesh sieve for laboratory analyses: dry matter (AOAC 1990, method 943.01), mineral matter (AOAC 1990, method 942.05), crude protein (AOAC 1990, method 920.87), ether extract (AOAC 1990, method 920.39A), neutral detergent fibre and acid detergent fibre, methodology described by Van Soest et al. (1991), modified by Ankom Technology, Fairport, NY (Pell and Schofield 1993). For estimation of total carbohydrates, non-fibre carbohydrates and total digestible nutrients, the equations in Sniffen et al. (1992), Hall (2000) and Weiss (1999) were used, respectively.
Sampling, collection and laboratory analysis The quantities of food provided and leftovers were recorded daily. Samples were collected weekly from the ingredients that made the concentrates, hay and leftovers per animal. Weekly samples were pre-dried in a forced ventilation oven at 55–60 °C for 72 h. At 100 days into the experiment, samples were collected from the digestibility trial for 10 days to determine the apparent digestibility of nutrient. To estimate the faecal dry matter Table 4
Coefficients of apparent digestibility of nutrients and total digestible nutrient content depending on the increasing levels of concentrate Concentrate levels (g/kg DM) r2
P
R.E.
1.4 4.7 9.4 7.6 2.1
0.976 0.956 0.953 0.991 0.957
0.000 0.001 0.000 0.000 0.000
y=58.035+0.3228x y=67.534+0.1634x y=45.298+0.5838x y=35.4999+0.5308x y=57.396+0.3123x
5.0 344.0
0.830 0.997
0.000 0.000
y=58.056+0.3456x y=52.585+0.3043x
170
340
510
680
CV (%)
Dry matter Neutral detergent fibre Crude protein Ether extract Organic matter
0.62 0.71 0.53 0.44 0.61
0.70 0.72 0.69 0.54 0.70
0.74 0.76 0.73 0.63 0.73
0.79 0.79 0.85 0.71 0.78
Non-fibre carbohydrates Total digestible nutrientsa
0.61 0.57
0.74 0.63
0.76 0.68
0.79 0.73
R.E. regression equations a
Observed form Weiss (1999)
1310 Table 5
Trop Anim Health Prod (2015) 47:1307–1312 Performance of crossbred cattle in feedlot due to rising levels of concentrate Concentrate levels (g/kg DM) 170
340
510
680
CV (%)
r2
P
R.E.
344
344
343
343
12.3
–
–
N.S.
Final body weight (kg)
449
459
489
504
12.5
–
–
N.S.
Total weight gain (kg) Average daily gain (kg/day)
105 0.86
115 0.95
145 1.22
161 1.34
18.6 19.8
0.965 0.964
0.001 0.001
y=82.5+1.1588x; y=0.6723+0.0099x
10.3
10.0
12.0
12.7
9.4
0.822
0.002
y=8.9688+0.054x
Initial body weight (kg)
Feed efficiency
N.S. means not significant. Indicate significant differences according to Tukey’s test (P≤0.05) R.E. regression equations
Performance evaluation, slaughter procedures and carcass evaluations After the adaptation period, five animals were slaughtered to obtain initial carcass weights in order to allow estimates of their respective gains. At the end of each 28-day period, the remaining animals were weighed after solid fasting for approximately 16 h to determine total weight gain and average daily gain. Feed efficiency was calculated as the ratio between the average daily gain (kg/day) and dry matter intake in kilogrammes per day. After 112 days, all animals were slaughtered. Slaughter was conducted in the city slaughterhouse of Serra Talhada, Pernambuco, Brazil, and followed the normal procedures of a slaughterhouse under state inspection. The carcass of each animal was divided into two half-carcasses, which were weighed to obtain the hot carcass yield and then cooled in a cold chamber at ±4 °C for 24 h. After this period, the half-carcasses were removed from the cold chamber and weighed to determine the cold carcass weight and cold carcass yield. The carcass gain was calculated considering the carcass weight obtained at slaughter minus the initial parameters of the reference animals. Table 6
The efficiency of carcass deposition was calculated as the ratio between the carcass gain and dry matter intake. The carcass deposition rate in kilogrammes per day was obtained by the ratio between the carcass gain and the days in the feedlot. Experimental design and statistical analysis The experimental design was completely randomized. Data were submitted to analysis of variance and regression using SAS statistical software version 9.1 (SAS Inst. Inc. 2009). The criterion used to select the model was the coefficient of determination (r2, in g/kg), and significance was estimated through the F test.
Results Dry matter intake (kg/day) increased linearly with the addition of concentrate (Table 3). Likewise, intake as a percentage of body weight (g/kg BW) and intake in terms of metabolic body weight (g/kg BW0.75).
Features of deposition and carcass yield of crossbred cattle depending on the increasing levels of concentrate Concentrate levels (g/kg DM) 170
340
510
680
CV (%)
r2
P
R.E.
Hot carcass weight (kg) Cold carcass weight (kg) Hot carcass yield (g/kg) Cold carcass yield (g/kg) Carcass gain (kg) Efficiency of carcass depositiona
245 237 0.54 0.52 85.6 8.3
255 251 0.55 0.54 99.9 8.5
282 277 0.57 0.56 125.9 10.2
290 285 0.57 0.56 134.0 10.6
13.7 13.4 3.0 2.0 31.6 20.3
0.954 0.965 0.858 0.858 0.965 0.904
0.041 0.027 0.004 0.000 0.027 0.043
y=272.04+0.9633x y=219.54+1.0074x y=53.42+0.0671x y=51.693+0.0798x y=68.54+1.0074x y=7.2933+0.0496x
Carcass deposition rate (kg/day) Gastrointestinal content (kg)
0.7 47.4
0.8 41.8
1.1 39.5
1.1 31.7
34.3 20.3
0.957 0.960
0.036 0.008
y=0.5644+0.0086x y=52.396−0.2894
R.E. regression equations a
The efficiency of carcass deposition was calculated as the ratio between the carcass gain and dry matter intake
Trop Anim Health Prod (2015) 47:1307–1312
The crude protein and total digestible nutrient intakes showed the same trend as DMI, rising 14.1 and 50 g, respectively, for every 10 g/kg concentrate. The neutral detergent fibre intake was linear and negatively influenced by the inclusion of concentrate in the diet, falling by 29 g with every increase of 10 g/kg concentrate. The results for apparent digestibility of nutrients are shown in Table 4. A positive linear and significant behaviour (P
