Article

Effect of CSN1S1 genotype and its interaction with diet energy level on milk production and quality in Girgentana goats fed ad libitum

Dipartimento di Scienze Agronomiche, Agrochimiche e delle Produzioni Animali (DACPA), University of Catania, Via Valdisavoia 5 95123 Catania, Italy.
Journal of Dairy Research (Impact Factor: 1.39). 05/2010; 77(2):245-51. DOI: 10.1017/S0022029910000129
Source: PubMed

ABSTRACT A study was carried out to evaluate how the energy level of the diet can affect milk production and quality in Girgentana lactating goats in relation to polymorphism at the alphas1-casein (CSN1S1) genotype locus. Twenty-seven goats, homogeneous for milk production (1.5+/-0.3 kg/d), days of lactation (90+/-10 d) and body weight (35.8+/-5.5 kg) were selected on the basis of their CSN1S1 genotype, as follows: nine goats homozygous for strong (AA) alleles, nine goats homozygous for weak alleles (FF) and nine goats heterozygous (AF). The goats were used in a 3x3 factorial arrangement of treatments, with three genotypes (AA, FF, AF) and three diets at different energy levels (100%, 65% and 30% of hay inclusion). The experiment consisted of three simultaneous 3x3 Latin squares for the three genotypes, with one square for each level of hay inclusion in the diet. All the animals were housed in individual pens. Each experimental period lasted 23 d and consisted of 15 d for adaptation and 8 d for data and sample collection, during which the goats received the scheduled diet ad libitum. The animals were fed three different diets designed to have the same crude protein content (about 15%) but different energy levels: a pelleted alfalfa hay (H100) and two feeds including 65% (H65) and 30% (H30) of alfalfa hay (respectively 1099, 1386 and 1590 kcal NE for lactation/kg DM). All the diets were ground and pelleted (6 mm diameter). AA goats were more productive than AF and FF goats (respectively: 1419 v. 1145 and 1014 g/d; P=0.002). Indeed the interaction energy levelxgenotype was significant (P=0.018): in fact AA goats showed their milk increase only when fed with concentrates. Differences in protein and in casein levels between the three genotypes were in line with results expected from the different allele contribution to alphas1-casein synthesis. Milk urea levels were significantly lower in AA goats compared with AF and FF genotypes (respectively 32.7 v. 40.4 and 40.4 mg/dl; P=0.049) and significantly lower when goats were fed with 65H and 30H diets than with 100H diet (respectively 37.4 and 34.3 v. 41.7 mg/dl; P<0.001). Indeed, a significant interaction genotypexdiet (P=0.043) occurred for milk urea, which was significantly lower in AA goats but only when fed with concentrates (65H and 30H). Blood concentrations of energy indicators (glucose, non-esterified fatty acids and beta-hydroxybutyric acid) were not influenced by genotype. The results confirm that strong alleles are associated with a greater efficiency of feed utilization and seem to show that a high energy level of the diet can further improve this efficiency.

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    • "Further to that, Pagano et al. (2010) observed differences in milk protein and caseins levels between three genotypes of CSN1S1 (homozygous for strong or weak alleles as well as heterozygous) in line with results expected from the different allele contribution. This conclusion was possible because the goats used in their study were genetically for the CSN1S2 and CSN2 (Pagano et al. 2010). However, in the present study the ewes were not genotyped or the milk caseins yields were not determined, so it is not possible to associate possible genetic variations with different rates of the corresponding proteins synthesis. "
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    ABSTRACT: Milk protein synthesis in the mammary gland involves expression of six major milk protein genes whose nutritional regulation remains poorly defined. In this study, the effect of long term under- and over-feeding on the expression of αs1-casein: CSN1S1, αs2-casein: CSN1S2, β-casein: CSN2, κ-casein: CSN3, α-lactalbumin: LALBA and β-lactoglobulin: BLG gene in sheep mammary tissue (MT) was examined. Twenty-four lactating dairy sheep, at 90-98 d in milk, were divided into three groups and fed the same ration, for 60 d, in quantities which met 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed a significant reduction on mRNA of CSN1S1, CSN1S2, CSN2 and BLG gene in the MT of underfed sheep compared with the overfed ones and a significant reduction in CSN3 and LALBA gene expression compared with the respective control animals. Significant positive correlations were observed between the mRNA levels of milk proteins' genes with the milk protein yield and milk yield respectively. In conclusion, the feeding level and consequently the nutrients availability, affected the milk protein yield and milk volume by altering the CSN1S1, CSN1S2, CSN2, CSN3, LALBA and BLG gene expression involved in their metabolic pathways.
    Journal of Dairy Research 07/2015; DOI:10.1017/S0022029915000333 · 1.39 Impact Factor
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    • "Schmidely et al. (1997) reported different values, even though not statistically significant, for different α S1 -CN genotypes (EE > FF > AA) and different diets (12% > 16% > 20% CP/DM) on plasma urea levels. Conversely, Pagano et al. (2010a) did not find an effect of CSN1S1 genotype on blood urea in goats fed iso-protein content diets. The CSN1S1 genotype and diet did not influence the amount of insulin in the blood, in agreement with results found by Schmidely et al. (1997) comparing the AA and FF genotypes. "
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    ABSTRACT: Polymorphism at the αS1-casein locus (CSN1S1) in goats influences several milk production traits. Milk from goats carrying strong alleles, which are associated with high αS1-casein (αS1-CN) synthesis, has higher fat and casein contents, longer coagulation time and higher curd firmness than milk from goats with weak alleles linked to low αS1-CN content. Nutrition also affects these milk properties; therefore, it is important to better understand the interaction between dietary characteristics and the CSN1S1 genotype in goats. This study aimed to investigate the effect of fresh forage based diet or energy supplement on feeding behavior, milk production, and metabolic and hormonal parameters of Girgentana goats with different genotypes at CSN1S1 loci. From a group of goats genotyped by PCR at the DNA level, 12 were selected because they had the same genotype for αS2-CN, β-CN, and κ-CN but a different genotype for αS1-CN: 6 were homozygous for strong alleles at the CSN1S1 loci (AA) and 6 were heterozygous for a weak allele (AF). Goats of each genotype were allocated to 3 subgroups and fed 3 diets ad libitum in a 3 × 3 Latin square design. The diets were sulla (Hedysarum coronarium L.) fresh forage, sulla fresh forage plus 800 g/d of barley meal (SFB), and mixed hay plus 800 g/d of barley meal (MHB). Diet had a stronger effect than CSN1S1 genotype. The SFB diet led to the highest energy intake, dry matter (DM) digestibility, and milk yield. The fresh forage diets (SFF and SFB) increased DM and crude protein (CP) intake, CP digestibility, and milk CN compared with the MHB diet. The diets supplemented with energy (SFB, MHB) reduced milk fat and urea, improved CP utilization for casein synthesis, and limited body fat mobilization, in accordance with a lower level of nonesterified fatty acids and higher levels of glucose and IGF-1. With regard to CSN1S1 genotype, AA goats showed higher CP digestibility and lower free thyroxine hormone and cholesterol levels than AF goats. Significant diet × genotype interactions indicated how AA goats, compared with AF goats, showed higher DM digestibility and milk yield when fed the SFB diet, which had more energy. A reduction in free triiodothyronine hormone occurred in AF goats fed the MHB diet, whereas no differences were observed in AA goats. These results demonstrate how goats with a higher capacity for αS1-CN synthesis exhibit more efficient energy and protein utilization, evident at the digestive level, and better productive responses to high-nutrition diets.
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    • "Previous studies have reported that the CSN1S1 can affect casein, protein, and fat levels, total solids, milk rheology, as well as cheese yield and quality (Pirisi et al. 1994; Clark & Sherbon, 2000; Martin et al. 2002; Roncada et al. 2002; Gómez-Ruiz et al. 2004; Zeng et al. 2007; Pagano et al. 2010). "
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